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MECHANICAL EQUIPMENT 



OF 



FEDERAL BUILDINGS 



UNDER THE CONTROL OF 



THE TREASURY DEPARTMENT 



(THIRD REVISED EDITION) 



BY 

NELSON S. THOMPSON 

Chief Mechanical and Electrical Engineer, Office of the 
Supervising Architect, Washington, D. C. 



NEW YORK 

HEATING AND VENTILATING MAGAZINE CO. 

1123 BROADWAY 









In presenting to the public the basic data used in designing 
the Mechanical Equipment for buildings under the control of 
the Treasury Department, I desire to give credit to N. R. 
Stansel, M. S. Cooley, H. M. Price, D. F. Atkins, A. R. Horn, 
H. C. Russell, E. L. Wilson, E. C. Stanton, C. R. Bradbury, 
J. L. Vawter, Myers Hand and L. A. Warren for their valuable 
contributions. 

NELSON S. THOMPSON 

Chief Mechanical and Electrical Engineer, 

Office Supervising Architect, 

Treasury Department 



Copyright, 1915, by Heating and Ventilating Magazine Co. 

DEC 1 3 1915 

©GI.A420050 



CONTENTS 

CHAPTEK 

I. Heating and ventilation 1 

II. Commercial practice in regard to heating factory and other 

buildings 75 

III. Commercial practice in regard to heating by forced circulation 

of hot water from a central station 124 

IV. Plumbing, drainage and water supply 137 

V. Gas piping 193 

VI. Conduit and wiring systems 197 

VII. Lighting fixtures 225 

VIII. Elevators 235 

IX . Small power plants 278 

X. Motors and controlling apparatus 306 

XI. Vacuum cleaning systems 316 

XII . Operating data 343 

Appendix — 

General instructions 363 

Suggestions to superintendents 373 

Miscellaneous data 383 

Index '. 399 



in 



CHAPTER I 
HEATING AND VENTILATION 

The office of the Supervising Architect, Treasury Department, 
used to install gravity indirect steam or hot water in practically 
all the smaller buildings which it erected, except where conditions 
precluded gravity indirect, and then direct-indirect was installed. 
In the large buildings mechanical ventilation supplemented with 
direct radiation was installed. 

All office rooms in all buildings and all assembly rooms were 
provided with heat and vent flues, and the entire building (except 
corridors) was ventilated. 

During this period designers had no opportunity to inspect the 
installations, which was a serious drawback in their work. Ob- 
servation of the various steps in the care and operation of the 
mechanical and electrical equipment of completed and occupied 
buildings would have been of special value to them. When such 
opportunity was later granted it was discovered that the theo- 
retical advantages of the system outlined above as applied to the 
smaller buildings were not secured in practice. 

In most instances it was found that the fresh air ducts and 
the base of the gravity indirect radiator chambers were seldom or 
never cleaned and in most cities there was so much soot and dust 
in the atmosphere that the walls around registers were black. 
The air coming out of the registers had a bad odor, and in gen- 
eral the system was not satisfactory. The dry air filters, which 
are alone practical with this system, proved most unsatisfactory. 1 

The manner of supplying air to the direct-indirect radiators 
was not satisfactory, and that system fell into disrepute on that 
account. Also, radiators froze in extreme cold weather. 

During this period the Federal buildings were of massive con- 
struction, and the cost of the heating and ventilating apparatus 
in the smaller buildings was not disproportionate to the total 

1 It must be understood that the office of the Supervising Architect 
did not at this time have the power of selecting the engineers or firemen, 
and had no direct control of them after their appointment. 

1 



2 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

cost of the building. Later, the massive masonry construction 
was abandoned and much cheaper buildings provided for, neces- 
sitating a reduction in the cost of the mechanical equipment. 
Contrary to the impression of the general public, unlimited funds 
are not available for the erection and equipment of government 
buildings, and in the very large majority of cases it is necessary 
to reduce the cost of the mechanical equipment to the lowest 
point, eliminating everything not absolutely essential. 

Under the present policy in regard to new buildings, all the 
rooms have at least 1800 cubic feet of space for each and every 
occupant, and in most cases electricity is used for illumination; 
and the area of the exposed windows and doors is always at least 
one-fourth the area of the floor. The main assembly room (post- 
office workroom) is frequently flushed out by the opening of ex- 
terior doors to admit and dispatch mails. 

In view of the foregoing it was decided to eliminate the venti- 
lating apparatus in the smaller buildings which were not provided 
with court rooms. In practically all the smaller buildings the 
steel smokestack of the boiler is placed inside of a brick shaft, 
and into this shaft openings provided with top and bottom reg- 
isters are made which serve to draw air from the post-office work- 
room, the large basement toilet-room, and the room in the base- 
ment in which the letter carriers remain when off duty. 

The small private toilet-rooms are used infrequently, and as 
they are provided with generous exterior windows vent flues are 
seldom installed. 

When a building contains a court room, gravity-indirect radia- 
tion is installed sufficient to change the air not less than twice an 
hour in court room, which is provided with a vent flue or flues, 
connected with the vent shaft. 

The court room is heated by direct radiation, the indirect merely 
heating the air to 75° F. 

Where conditions preclude the installation of gravity-indirect 
stacks for the court room direct-indirect radiators are installed 
to supply ventilation and vent flues as above noted are installed 
also. 

In the large buildings all the heating is done by direct radia- 
tion, and the fresh air is admitted to the rooms to be ventilated 
at about 75° F. The ventilation in the large buildings is con- 



HEATING AND VENTILATION 3 

fined mainly to the postoffice workrooms and the court rooms 
(rooms in which a number of people assemble) , and the principal 
office rooms. 

The advantages of this system are that the ventilating appara- 
tus may be shut down from, say, 6 p.m. to 8 a.m., and the direct 
radiation kept in service continuously in order to prevent the 
building cooling off. An accident to the fan motor does not 
cripple the entire heating and ventilating system as is the case 
with the straight hot-blast system. 

In the larger buildings the post-office section is in operation 
night and day continuously, and it is imperative that sufficient 
heat be obtainable at all times. 

In several of the large buildings constructed by the office in 
earlier days the vent flues from the office rooms were omitted, 
and the fresh air which was forced in by the fan found an outlet 
through crevices around windows and entrance doors. This is 
now overcome by installing metal weather-strips in all buildings 
provided with mechanical ventilation, and, wherever the con- 
struction permits, installing vent flues from the apartments sup- 
plied with fresh air. 

Even with metal weather strips, when air is admitted for ven- 
tilation only, it is not deemed absolutely necessary to install vent 
flues in each office room. The vent flues or registers provided in 
the assembly rooms and main toilet-rooms are ample to carry 
off all the air forced in by the fan. 

Vent registers installed in entrance doors from corridors are 
regarded as useless and unsightly. 

In all buildings equipped with a plenum fan the practice is to 
install an air washer, as such a device is looked upon as the most 
essential feature of a successful ventilating apparatus. The old 
ventilating apparatuses were a failure on account of the inability 
of the dry air filter to cleanse the air properly. In a test recently 
made by a representative of the office of the Supervising Archi- 
tect a new cheese-cloth filter reduced the delivery of the fan 25 
per cent when air was passing through the filter at the rate of 2 
feet per second. 

No heating and ventilating apparatus is complete without some 
means of absolutely and automatically controlling the tempera- 
ture of the apartments, and when funds are available a first-class 



4 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

automatic temperature-controlling apparatus is installed in the 
larger buildings. Aside from the comfort thus assured, a saving 
of not less than 10 per cent in the coal pile may be secured. 

When it is certain that an automatic temperature-controlling 
apparatus is to be installed, the radiation is not split into small 
units as is the case when hand control only is to be used, and 
the reduction in the number of units offsets in a measure the cost 
of the automatic temperature-controlling apparatus. 

The method adopted by the office for controlling the tempera- 
ture of the tempering and reheating coils when air for ventilation 
only is to be supplied is as follows : 

Provision is made for a by-pass damper or dampers under both 
the tempering and reheating coils. The dampers are made equal 
in area to not less than 10 per cent of the gross area of the coils 
and not larger than 15 per cent of said gross area. All dampers 
larger than 20 inches x 36 inches are made of the louvre type. 
The tempering coils are made deep enough to heat the air from 
the lowest local temperature on record to 67° F., and the reheat- 
ing coils deep enough to heat the air from 50° to 80° F. This 
arrangement allows for a 20° temperature drop due to air passing 
through the air washer. 

To control the tempered air a thermostat is installed in the 
cold-air chamber, and is set to open the first row of coils when 
outside air is 40° F. This is a refinement which may be omitted 
if desired and hand-control valves only used on this section. 

Two thermostats are installed between the air washer and the 
secondary or reheating coils. One is set at 45° F. to shut off the 
inside row or rows of tempering coils when air reaches that tem- 
perature after passing through the air washer; the other is set at 
47° F. and operates the by-pass damper under the tempering coils. 
These thermostats are placed beyond the air washer so that the 
air will not become too saturated in cold weather. 

The secondary coils are generally two or three sections deep, 
and one two-point thermostat is set near the fan inlet to control 
the steam inlet valves on same. One point of this multiple ther- 
mostat is set at 71° F. and shuts off the first row when air reaches 
that temperature; the second point is set at 73° F. and controls 
the second row of coils, or the second and third rows, as the case 
may be. A thermostat is also placed near the fan inlet and set 



HEATING AND VENTILATION D 

at 75° F. ; and when air reaches that temperature it opens the by- 
pass damper under the secondary heating coils. 

All thermostats have a range of 15° on each side of the point set, 
and those on the steam valves are positive and have a quick 
movement to open or shut the valves. The by-pass damper 
thermostats are of the gradual-moving or intermediate type. 

The control where a plenum chamber or school-house system is 
used is the same as noted above in so far as the tempering coils 
and the by-pass under same are concerned, but on the reheating 
coils no automatic control is used and the valves on coils are hand- 
control type, or diaphragm type controlled by hand by three-way 
cocks. The temperature of the hot air is read on a thermometer 
in the hot-air chamber, and the engineer controls the reheating 
coils by hand. 

In the ordinary office rooms one thermostat is placed to control 
the direct radiation. In large court rooms and in post-office work- 
rooms two or more thermostats are placed, according to the judg- 
ment of the engineer in charge of the drafting room. 

When a hot-water heating system is equipped with an auto- 
matic temperature controlling apparatus, the diaphragm valve is 
placed on the return end of radiators. 

Complaints may be expected during the first season an auto- 
matic temperature-controlling apparatus is in use in a building, 
as the occupants throw the thermostats out of adjustment, owing 
to unfamiliarity with the workings of the system. As soon as 
they have acquired sufficient experience to avoid this, the appara- 
tus invariably gives satisfaction. 

Attention is called to the fact that the automatic temperature- 
controlling apparatus must be of the very highest grade, or it 
will be worse than useless. 

In connection with installing automatic temperature control on 
a low-pressure heating apparatus, the office will install an air- 
removal system with a water-operated vacuum pump on jobs con- 
taining 2000 square feet and less, and for over 2000 square feet, 
an electrically-operated air exhauster. The patents have ex- 
pired on this system where no pressure-reducing valve is used; 
therefore no royalty is required. 

This system is especially desirable when automatic temperature 
control is used, and is being placed in the large buildings where 



6 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

low-pressure steam is generated, even when not provided with 
automatic temperature control, to assist in air removal and in- 
sure quick heating. 

In large buildings where an electric generating plant is to be 
installed an air-line system, or one of the standard vacuum sys- 
tems with special valve on return end of each radiator is installed. 
This reduces the back-pressure on the engine and insures quick 
heating of a large amount of radiating surface. These devices, 
under the conditions noted above, are a satisfactory and econom- 
ical adjunct to the mechanical equipment. 

The office does not regard with favor the various atmospheric 
or vapor systems of steam heating on the market as applied to 
plants in small Federal buildings, for the reason that under the 
usual operating conditions few or none of the advantages claimed 
for these systems would be secured. As an experiment, the 
office has installed a number of vapor systems of different makes, 
and their operation in actual service will be checked against the 
claims made for them. The argument advanced for most of the 
vapor systems, i.e., that a certain amount of temperature control 
is thereby secured, is not given much weight by the office, as prac- 
tical heating engineers are aware that hand manipulation of 
valves by individuals to secure temperature control is generally 
unsatisfactory. 

In the smaller buildings the standard one-pipe gravity-return 
steam heating apparatus, such as installed by the office, gives 
first-class results, as it is simple in construction and operation, 
and will circulate at atmospheric pressure. 

When automatic temperature control can not be used, the office 
endeavors to secure a certain amount of temperature control in 
connection with its steam heating systems by installing at least 
two radiators in all apartments with two or more windows, so 
that in mild weather one radiator may be shut off and remain 
out of service. This is, of course, a makeshift, but it is the best 
solution when funds are limited. 

When money is available for the purpose, the practice of the 
office will be to use hot air as the heating medium for buildings 
located on the Pacific coast south of Los Angeles, and on the 
Florida peninsula; otherwise direct steam will be used. 

In localities where the lowest recorded temperature is not be- 



HEATING AND VENTILATION 7 

low 10° F., and sudden changes are not common, direct hot water 
will be used; and in cities where there is a district heating com- 
pany, using hot water as the heating medium, hot water will 
be used without reference to climatic conditions. 

With the above exceptions, steam heating is used, and experi- 
ence has demonstrated that under all conditions it is generally 
more satisfactory in operation than any other system in Federal 
buildings. 

If a district heating system is in operation in a city in which a 
Federal building is to be erected or remodeled, the heating ap- 
paratus is so designed that it may be operated from the district 
heating system or from boilers installed in the building. The 
boilers are always installed, to serve as a check on the cost of 
outside service and for use in case of a break-down in the district 
system; but usually it is equally economical and more satisfac- 
tory to purchase steam or water for heating rather than to gener- 
ate it in the boilers provided. 

The practice of the office is to ascertain the amount of radia- 
tion required by the B.t.u. method, and the results are checked 
by the experience and judgment of the chief mechanical and 
electrical engineer. 

BASIS FOR CALCULATING RADIATING SURFACE 

Lowest temperature on record in the locality is ascertained from 
the Weather Bureau reports. If the city has no station the re- 
sults are taken from the nearest station thereto. 

In southern cities, where the lowest recorded temperature oc- 
curs infrequently, and then only for a day or two, the calculation 
is based on a temperature 10° in excess of the lowest on record for 
the previous ten years. 

In northern cities where the temperature goes below 10° and 
remains around zero for several days, the calculation is based on 
lowest temperature recorded during the previous ten years. 

All office rooms, the post-office workroom, court rooms, corri- 
dors, lobbies, letter carriers' swing room, and all toilet-rooms con- 
taining bathing facilities are heated to 70° F. General toilet- 
rooms which do not contain bathing facilities are never heated 
above 60° F. In southern latitudes where the calculation is 



8 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

based on 20° F. or above heat is not provided for any toilet room 
except that for the carriers. Small toilet-rooms which open 
from office rooms are not provided with heat where lowest re- 
corded temperature is not below zero. 

After determining the temperature upon which the calculation 
is to be based, the heat losses are ascertained by the B.t.u. method, 
using the following coefficients for glass and wall, etc., based on 
Prof. Homer Woodbridge's calculations of heat transmission per 
degree difference in temperature between inside and outside air: 

SOLID BRICK WALL 

Inches One wall exposed Two walls exposed 

12 0.265 0.232 

18 0.210 0.205 

21 0.187 0.185 

24 0.167 0.150 

27 0.152 0.140 

30 0.140 0.130 

33 0.130 0.120 

36 0.120 0.113 

40 0.112 0.103 

HOLLOW BRICK WALL 
Inches One wall exposed Two walls exposed 

12 0.220 0.170 

18 0.175 0.137 

21 0.160 0.125 

24 0.147 0.115 

27 0.135 0.105 

30 0.125 0.097 

33 0.117 0.090 

36 0.110 0.084 

40 0.100 0.077 

SOLID GRANITE OR MARBLE WALL 
Inches One wall exposed Two walls exposed 

12 0.400 0.335 

18 0.340 0.290 

21 0.315 0.275 

24 0.295 0.260 

27 0.280 0.245 

30 0.265 0.232 

33 0.250 0.220 

36 0.235 0.210 

40 0.220 0.200 



HEATING AND VENTILATION 9 

HOLLOW GRANITE OR MARBLE WALL 
Inches One wall exposed Two walls exposed 

12 '. 0.305 0.245 

18 • 0.270 0.215 

21 0.255 0.202 

24. 0.240 0.190 

27. 0.228 0.180 

30 0.218 0.172 

33 0.208 0.164 

36 0.200 0.157 

40 0.190 0.149 

BRICK .WALLS WITH SANDSTONE FACES, PLASTERED ON INSIDE 

Brickwork Thickness of sandstone face 

Inches 4 inches 8 inches 12 inches 

4 0.31 0.29 0.26 

8 0.22 0.20 0.19 

12 0.17 0.16 0.15 

Concrete or 
Inches sandstone Limestone 

12.. 0.45 0.49 

16.. .' 0.39 0.43 

20.. 0.35 0.38 

24 0.31 0.35 

28. 0.28 0.31 

32 0.26 0.28 

36 0.24 0.26 

40 0.22 0.24 

Above constants are for walls furred and plastered on the in- 
side with 2-inch terra cotta or wood furring. For walls not 
furred or plastered add 20 per cent; plastered only add 15 per cent. 

Outside walls of frame buildings, lath and plaster inside, out- 
side construction as below: 

Ordinary overlapping clapboards — ^ inch thick 0.44 

Same with paper lining . 31 

Same with f-inch sheathing . 28 

Same with f-inch sheathing and paper 0.23 

Inside partitions consisting of 4-inch studs with lath and plas- 
ter on one side and the other side as below : 

Nothing 0.60 

Lath and plaster .34 



10 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

For various roof surfaces, as follows : 

Slate on wood for framing only .80 

Slate on tight wood sheathing 0.30 

Iron on wood for framing only 1 .32 

Iron on tight wood sheathing . 17 

Patent roof (tar and gravel, paper, etc.) 0.30 

Tiling f-inch to 1-inch thick. . '. .80 

Six-inch hollow tile — 2-inch concrete and tar and gravel 

covering . 36 

Eight-inch hollow tile — 2-inch concrete and tar and gravel 

covering . 40 

Four-inch concrete with cinder fill 0.60 

Six-inch concrete with cinder fill .54 

For various floor surfaces, as follows, assuming temperature of 
unheated spaces as 40°: 

Cement or tile ( no wood above) .31 

Cement or tile (wood floors above) 0.08 

Dirt (no floor whatever) . 23 

Ordinary, single, wood near ground 0.10 

Wood, single, no plaster beneath joists 0.10 

Wood, double, no plaster beneath joists 0.08 

Wood, single, with plaster beneath joists 0.08 

Wood, double, with plaster beneath joists 0.06 

For various ceilings as follows, assuming temperature of attics 
as 30° above lowest outside temperature : 

Cement or tile (no wood above) .39 

Cement or tile (wood floor above) . 10 

Lath and plaster (no floor above) .32 

Lath and plaster (single floor above) 0.26 

Fireproof ceiling (metal lath, no wood above) 0.49 

Fireproof ceiling (metal lath, wood floor above) . 15 

For various glass surfaces as follows, assuming exterior doors 
same as glass, and measuring the openings in brickwork for glass 
surface : 

Glass in single windows 1 .00 

Glass in double windows 0.50 

Glass in single skylight 1 .50 

Glass in double skylight 0.50 

Glass in single monitor 1 .35 



HEATING AND VENTILATION 11 

In rooms over 12 feet high the heat loss is increased by an 
amount due to the rise in the mean internal temperature, and by 
the increased rate of air movement over the interior surface of 
the wall. This increase is practically 2 per cent for each foot of 
ceiling height over 12 feet. 

The preceding tables are for southern exposure. Maximum 
allowance for other exposures should be made as follows : 

Per cent 

North, add 25 

West, add 15 

East, add 10 

To this add the following for loss due to leakage : 

Per cent 

For office rooms 35 

For main lobby, post-office workroom, and court-room 50 

Allow for direct steam radiation, standard 3-column radiator, 
250 B.t.u., for 2-column 260 B.t.u., and for single-column 270 
B.t.u. per square foot per hour; and for water, 160 B.t.u. for 3- 
column, 170 B.t.u. for 2-column, and 180 B.t.u. for single-col- 
umn radiation. 

If a direct radiator is inclosed in a window breast with a proper 
arrangement for circulating air over it, allow 200 B.t.u. for steam 
and 120 B.t.u. for water. Three square inches net area in regis- 
ters or grills to concealed radiators are allowed per square foot of 
radiating surface. 

If a direct radiator is to be placed under a window seat, 220 
B.t.u. are allowed for steam, and 140 B.t.u. for hot water 
radiation. 

The foregoing rules are not applicable when a building is pro- 
vided with metal weather strips. In such cases the following 
formula is used : 

G = area of glass in square feet. 

W = area of wall in square feet, less glass. 

10 = A constant for all brick walls up to 24 inches thick. 

30 = a constant for ceilings. 

T = temperature of room (70°). 

T\ = temperature of steam (210°). 

t = lowest outside temperature. 



12 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

The square feet of direct steam radiation required for all aver- 

/ w C\ T — t 

age-size office rooms = I G + — + — 



10 30/ Tj-T 

For first-floor lobbies, post-office workrooms, court rooms, and 
large office rooms add 25 per cent to the result obtained above. 

If there is a skylight in the room, divide the area of skylight 
by 5 if steam is the heating medium and add the result to the 
above formula. 

No allowance is made for exposure to north, west, or east. 

As a rule the above will check closely with the results obtained 
by ascertaining the radiation required by the B.t.u. method pre- 
viously given and then deducting 10 per cent for use of metal 
weather strips. 

The rule used for Federal buildings by the representative of 
one of the most prominent metal weather-strip manufacturers is 
as follows: 

G = area of class in square feet. 
W = area of wall in square feet, less glass. 
C = ceiling in square feet. 
to = a constant. 
4 = a constant. 
12 = a constant. 
0.44 = a constant for steam. 
. 6 = a constant for hot water. 

Direct radiation = ( — - + — - + — ) X 0.44 for steam and 0.6 for 

\ J-U TC *-^ / 

hot water. 

This rule is used by the company where the lowest temperature 
on record is — 10° to 0°. No allowance is made for exposure. 

Direct-indirect radiation. For direct-indirect heating, a speed 
of 5 feet per second through the cold-air inlet duct to the radiator 
is assumed, to ascertain the amount of air which must be raised 
from exterior temperature to that of the room. This speed has 
been observed in several anemometer tests of these systems. 

The heat losses through wall and glass are ascertained by using 
the exposure factor the same as in direct radiation, but in lieu 
of using leakage factors the number of B.t.u. required to raise the 
temperature of air introduced through radiator from lowest re- 



HEATING AND VENTILATION 13 

corded exterior temperature to room temperature is ascertained. 
Three hundred B.t.u. per square foot for steam radiators and 
200 for hot water are allowed. In selecting the boiler the direct- 
indirect is reduced to direct equivalent by adding 20 per cent to 
the actual direct-indirect radiation installed. 

Vent flues with a positive outflow, such as is created by a fan 
or an aspirating coil, must be provided to assist the inflow of air 
through the direct-indirect radiators. A speed of 3 feet per sec- 
ond in vent flues connected to a properly located roof ventilator 
without aspirating coil is allowed. 

This system is sometimes employed with hot-water heating 
apparatus, but where the lowest temperature on record is below 
5° F. its use is not desirable on account of the danger of freezing 
the radiators. 

Gravity indirect radiation. Assume that the temperature of 
entering air under extreme outside conditions will be 120° F. for 
steam and 100° F. for hot water. 

The amount of radiation to install is ascertained by the B.t.u. 
method, taking into account the heat losses through wall, glass, 
and ceiling, and making allowance for exposure; and in addition 
allowing 10 per cent for loss of hot air through window cracks if 
metal weather strips are not used. The B.t.u. ascertained as 
above, multiplied by 55, and divided by 50 for steam and 30 for 
hot water, will give the number of cubic feet of air which must be 
admitted to the apartment per hour to heat it. 

The number of B.t.u. required to raise the temperature of the 
air from the lowest outside temperature to 120° F. for steam and 
100° F. for water, plus 5° allowance for temperature drop in flue, 
is ascertained and the resulting number of B.t.u. divided by 350 
for steam indirect, natural draft, and by 220 for hot water indi- 
rect, natural draft. 

The size of hot-air flues and ducts to be installed is ascertained 
by assuming the following speeds : 

Air speed to first floor, 200 feet per minute. 
Air speed to second floor, 300 feet per minute. 
Air speed to third floor, 400 feet per minute. 

The vent flues (which are always installed with this system) 
and cold-air ducts are made the same size as hot-air flues. 



14 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



In climates where the lowest temperature is —10° F. and be- 
low, 12-inch or 15-inch deep extended-pin radiators are used for 
steam, and in all climates similar radiators are used for water. 
For climates where temperature is below — 10° F. two 12-inch 
deep radiators are used for hot water. 

The allowable speed through cast-iron pin-indirect radiators for 
natural draft is limited to approximately 2 feet per second through 
one section deep. High speeds necessitate the placing of one sec- 
tion on top of another with a space of about 4 inches between the 
sections. Five feet per second through the radiator is the limit 
with natural draft. 

The check rule for indirect flues when room is to be heated by 
hot air is to make same equal in square inches to the area of glass 
in square feet plus one-fourth the area of exposed wall in square 
feet; no flue to be wider than three times its depth. The check 
rule to determine amount of indirect radiation is to divide the 
cubic feet of air to be delivered per hour by 200 when air must 
heat and ventilate the room and by 300 when air is for ventila- 
tion only. 

None of the cast-iron extended-pin indirect radiators (except 
the "Vento") contain the amount of surface given in the manu- 
facturers' catalogues, and, to be conservative, 20 per cent of the 
amount claimed should be deducted in making the layout. 



DIMENSIONS OF PIPING 
One-Pipe Steam Mains for Runs up to 200 Feet in Length 



SIZE OF FLOW PIPE 


RADIATION 


DRY RETURN 


WET RETURN 


inches 




inches 


inches 


2 


286 


ii 




2| 


535 


l* 




3 


890 


i* 




Si 


1,360 


2 




4 


1,950 


2 




5 


3,600 


2h 


1 1 

x 4 


6 


5,900 


3 


1 1 

A 2 


8 


12,700 


4 


2 


10 


22,900 


5 


2h 


12 


37,000 


6 


3 



HEATING AND VENTILATION 



15 



For other lengths of runs see formula given with the 2-pipe 
schedule. In patent steel steam boilers two tappings are used 
of such size as to keep velocity of steam in the verticals down to 
not over 20 feet per second. 

ONE-PIPE DIRECT RADIATOR TAPPINGS, ARMS AND RISERS 



SQUARE FEET 


TAPPING 


RISER AND ARM IN BASEMENT 
AND RADIATOR ARM 




inches 


inches 


0- 20 


1 


1 


21- 24 


1 


li 


25- 40 


U 


11 


41- 60 


li 


11 


61- 80 


li 


li 


81-100 


n 


2 


101-200 


2 


2 • 



TWO-PIPE HOT-WATER BASEMENT MAINS, GRAVITY CIRCU- 
LATION, DIRECT RADIATOR TAPPINGS 



FIRST FLOOR 


SECOND FLOOR 


THIRD FLOOR 


FOURTH FLOOR 


PIPE SIZE 










inches 


40 


50 


60 


70 


3 

4 


70 


80 


90 


100 


1 


110 


120 


135 


150 


U 


180 


195 


210 


230 


il 


300 


350 


400 


500 


2 



At ends of mains increase tapping one size. No main to be 



less than lj inches. 



To get size of mains and risers serving more than one radiator, 
add area of tappings together and use the following : 



nch.es 


EQUALIZING 


TABLE 

Inches 


\ equals 


2 


3 equals 175 


| equals 


5 


3| equals 260 


1 equals 


10 


4 equals 380 


\\ equals 


20 


5 equals 650 


\\ equals 


30 


6 equals 1,050 


2 equals 


60 


7 equals 1,600 


2\ equals 


110 


8 equals 2,250 



16 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

To get size pipe to serve a f-inch pipe and a 1-inch pipe: 

f inch equals 5 
1 inch equals 10 

15 equals 1| inch 

Expansion tanks are made 1 gallon to 30 square feet radiation 
up to 1000 square feet; 1 gallon to 40 square feet 1000 to 2000 
square feet; 1 gallon to 50 square feet 2000 to 5000 square feet 
and 1 gallon to 60 square feet for jobs above 5000 square feet in 
radiators. 

SCHEDULE OF SIZES TO BE USED ON DOWN FEED SINGLE DROP 
RISERS, RADIATORS, TAPPING, ETC. 

In the case of down flow single risers, tap radiators for all floors 
above the first, top and bottom on the same end, first floor radia- 
tors to have top floor connection on one end and bottom return 
on opposite end. 

Radiators 50 square feet and smaller to have f inch connection. 
Radiators 51 to 80 square feet to have 1 inch connection. 
Radiators 81 to 120 square feet to have 1| inch connection. 
Radiators 121 to 195 square feet to have 1| inch connection. 

Mailing vestibule radiators to be tapped one pipe size larger 
than the above. 

Drop risers to be made one size from flow to return main with 
standard cast iron tee fittings useid at th^ branch connections. 
The return branch from first floor and basement radiators to be 
connected to return main and not to risers, except in special 
cases where such branch connections would be of excessive length. 
Consult assistant engineer if such connections are over five feet. 

Make branches in attic and drop risers in accordance with the 
following schedule: 



50 square feet f inch. 

80 square feet 1 inch. 
120 square feet 1J inch. 
195 square feet 1| inch. 
350 square feet 2 inch. 



HEATING AND VENTILATION 17 

The attic distributing mains to be proportioned by adding to- 
gether the values given each size pipe in the equalization table, 
beginning at the far end of the main and adding together the risers 
values as you proceed. If the length of run to the last riser on 
the line exceeds 10 feet said run to riser must be increased one 
size above that of the riser up to lj inches in size. Riser 1| inches 
diameter will not require such increase. 

Return mains in the basement are to be reversed so that the 
first riser on the attic main becomes the last on basement main. 
Return mains are to be proportioned the same as above described 
for attic mains, care being taken to disregard the separate return 
branches from first floor and basement radiators, which are really 
provided for in the sizes of the riser branch. 

Radiators to be valved on both flow and return connection. 

The size of main riser may be taken from the following table, 
and may be greatly reduced in size if a proper chamber, or the 
expansion tank, is placed at the top of the main riser. 

Square feet 
direct 
Inches radiation 

3| 2,500 

4 3,500 

5 6,000 

2,000 6 10,000 



Inches 

n 


Square feet 

direct 

radiation 

300 


2 


600 


2£ 


1,200 



Expansion tanks are made 25 per cent larger than for two-pipe 
basement mains. 

One-pipe circuit hot water. Use the same tappings and risers 
as given for 2-pipe hot water. 

To arrive at size of 1-pipe circuit hot-water mains, the follow- 
ing sizes are used: 



Pipe 


200-foot 


300-foot 


Pipe 


200-foot 


300-foo1 


sizes 


runs 


runs 


sizes 


runs 


runs 


2 


200 


180 


5 


2,300 


1,800 


2^ 

^2 


400 


300 


6 


3,600 


3,000 


3 


600 


500 


7 


5,200 


4,000 


3§ 


900 


700 


8 


6,800 


6,000 


4 


1,200 


1,000 









A 1-inch or lj-inch starting pipe is used with this system. 
The length of mains is measured back to boiler. 



18 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



Tees on main are kept 2 feet apart. Risers are taken out of 
main on 45° and first floor connections out of top of main. All 
returns are taken into side of main. No special fittings are used 
except twin ells on mains where they branch. 

Two-pipe gravity steam. Radiators assumed to transmit 250 
heat units per square foot per hour. The following table is for 
pipes 200 feet in length. For pipes of greater length, multiply 

results in table by , in which "e" equals length in feet. The 

e 

values of this expression for different lengths of pipe are: For 

300 feet multiply by 0.66f ; for 400 feet, by 0.50; for 500 feet, by 

0.40; for 600 feet, by 0.33; for 800 feet, by 0.25; for 1000 feet, by 

0.20. 

TABLE FOR MAINS, RISERS, AND TAPPINGS FOR TWO-PIPE 

DRY RETURN STEAM HEATING SYSTEM, TWO POUNDS 

AND FIVE POUNDS STEAM PRESSURE 







TWO POUNDS 




FIVE POUNDS 




DIAMETEB 


DIAMETEB OF 


PRESSURE, 


RADIATING SUR- 


PRESSURE, 


RADIATING SUR- 


OF SUPPLY 


KETURN IN 


TOTAL HEAT 


FACE IN 


TOTAL HEAT 


FACE IN 


IN INCHES 


INCHES 


TRANSMITTED, 
B.T.U. PERHOUR 


SQUARE FEET 


TRANSMITTED, 
B.T.U. PER HOUR 


SQUARE FEET 


3 

4 


3 

4 


5,000 


20 


10,000 


40 


1 


3 

4 


9,000 


36 


15,000 


60 


H 


1 


18,000 


72 


30,000 


120 


14 


H 


30,000 


120 


50,000 


200 


2 


U 


70,000 


280 


120,000 


480 


2i 


2 


132,000 


529 


220,000 


880 


3 


24 


225,000 


900 


375,000 


1,500 


34 


24 


330,000 


1,320 


550,000 


2,200 


4 


3 


480,000 


1,920 


800,000 


3,200 


4| 


3 


690,000 


2,760 


1,150,000 


4,600 


5 


3| 


930,000 


3,720 


1,550,000 


6,200 


6 


3| 


1,500,000 


6,000 


2,500,000 


10,000 


7 


4 


2,250,000 


9,000 


3,750,000 


15,000 


8 


4 


3,200,000 


12,800 


5,400,000 


21,600 


9 


4A 


4,450,000 


17,800 


7,500,000 


30,000 


10 


5 


5,800,000 


23,200 


9,750,000 


39,000 


12 


6 


9,250,000 


31,000 


15,500,000 


62,000 


14 


7 


13,500,000 


54,000 


23,000,000 


92,000 


16 


8 


19,000,000 


76,000 


32,500,000 


130,000 



Cast-iron boilers. As the experience of the office has demon- 
strated that cast-iron sectional boilers are usually unsatisfactory 



HEATING AND VENTILATION 19 

in maintaining a steady water line and frequently crack and 
break under service conditions, they are used only where struc- 
tural reasons forbid the installation of steel boilers, and in such 
cases the proper size is ascertained by adding to the actual direct 
radiation installed 25 per cent for mains if anthracite coal is used, 
and 35 per cent if soft coal is used; and installing two boilers, each 
rated to carry two-thirds of the required service. Either boiler 
will then, if forced, carry the radiation for a few days in case of a 
breakdown in the other boiler. 

To obtain the size of the stack when cast-iron sectional boilers 
are used, the formula is: 

area of grate in square feet X 0.75 



Area in square feet 



V height of stack in feet 



The tappings for steam connections are made not less than two 
in number, and their area must be such that the velocity of steam 
will not be over 12 feet per second in the verticals. 

Returns are connected into both sides of each cast-iron boiler. 

A 2-inch equalizing pipe from the bottom of the main header 
into the main return header is always installed on patent steel 
or cast iron boilers. 

Fire box boilers. After an extended experience the office has 
adopted steel fire box boilers as a standard for all jobs of less than 
3600 square feet steam radiation or 6000 square feet water radia- 
tion. Above this two such boilers are used or horizontal return 
tubular brickset boilers are used. 

The fire box boilers are brickset with return smoke passage 
over top. 

One reason for the adoption of the fire box boilers was the ease 
and cheapness with which they are equipped with an effective 
down draft furnace and the low water line obtainable in such 
cases thus avoiding a pit in almost every case. 

These boilers have proven to be very efficient as to fuel and 
are no more expensive to install than the portable steel boilers 
and, ratings considered, but little more expensive than cast iron. 
Equipped with a down draft furnace they are cheaper than the 
portable steel boilers or horizontal return tubular either. 

These fire box boilers are drawn and specified on miscellaneous 
drawings No. 303 A and 304A, Supervising Architect's Office. 



20 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Portable steel boilers. In small buildings in which a down draft 
furnace is not used, consideration is given to a round vertical 
steel boiler. Except in certain special cases, the maximum size 
used of this type of boiler has a 28-inch diameter grate. 

In order to comply with local smoke ordinances, now existing 
in nearly every city of any size, down-draft furnaces are installed 
where soft coal must be used, except where the size of horizontal 
boiler required is such as to serve less than 1600 square feet of 
direct steam radiation. In such cases the Federal building is 
approximately the same size as a large residence, and, like a resi- 
dence, local smoke ordinances are not applicable thereto. 

The down-draft type of furnace is peculiarly suited to low- 
pressure heating boilers, as it has no moving parts, and a low 
grade of labor can be taught to fire it properly. 

Where small size anthracite coal is the cheapest fuel, the maxi- 
mum openings in the grate bars are specified not to exceed yq inch. 
The size of boiler when small anthracite coal is to be used is ob- 
tained by adding ^5 per cent to the actual direct radiation in- 
stalled. 

When the cost of 20,000 cubic feet of natural gas is cheaper 
than one ton of coal, the boiler is equipped with burners, pilot 
light, and governor. The rating of boiler for use with gas is as- 
certained by adding 25 per cent to the actual direct radiation 
installed. 

When bituminous coal is the cheapest fuel, the boiler rating is 
obtained by adding 25 per cent to the actual amount of direct 
radiation installed. 

When three times the cost of oil per barrel plus the cost of 
seven kilowatt-hours of electric current per day (generally 70 
cents) is less than the cost of one ton of coal, oil is used and the 
boiler is equipped with oil burners, pumps, tanks, etc. The office 
is reluctant to install oil burning apparatus, as it involves the use 
of motor and pump, which the class of labor employed in the 
small Federal buildings is not, as a rule, competent to handle. 
Unless the annual saving of oil over coal will amount to at least 
$200 per year, coal is used. 

The size of boiler for use with oil is ascertained by adding 25 
per cent to the actual direct radiation installed. 

When the size of the steel boiler required exceeds 3300 square 



HEATING AND VENTILATION 21 

feet, consideration is given to the advisability of installing (1) two 
small, steel boilers, (2) or a horizontal return-tubular brick-set 
boiler. 

All the ratings given above are direct steam ratings, but the 
remarks apply to hot water boilers of equivalent capacities. 

If a horizontal, return-tubular, brick-set boiler is to be installed, 
it is proportioned as follows: 

R = total direct radiation in building, in square feet. 
R.H.S. = 'heating surface in boiler, in square feet. 
G = area of grate in square feet. 

B.H.S. = — for small and — - for large steam boilers = — for 
8 10 15 

water. 

,- B.H.S. . B.H.S. , . , 

G = 3Q to plain grate. 

Lower grate of a down draft furnace is made same size as upper 
grate, which is never specified, it being preferred to allow the 
manufacturer to fix the size of the down draft furnace for the work 
to be performed. 

A down draft furnace increases the steaming capacity of a boiler 
15 per cent over ratings given above. 

H = height of stack in feet. 

A = area of grate in square feet. 

S = area of stack in square feet. 

S = —T=ior anthracite coal, lump coal, oil, and gas. 

S = /— X 1.25 for bituminous and small anthracite. 

For anthracite, pea, or rice coal, the tube area must be not less 
than one-eighth grate area and be always larger than stack area. 

For boilers with down-draft furnace attached, the tube area 
must be not less than one-sixth area of lower grate, and be always 
larger than stack area. 

Maximum length of tube must generally not exceed 48 diame- 
ters. 



22 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Maximum length of boilers 54-inch diameter and under must 
generally not exceed 3 diameters; over 54-inch 2| diameters. 

Tubes an odd number of feet long are not used. 

Coal consumption for low-pressure heating apparatuses in tons 
per heating season may be found for Government buildings by 
multiplying by 5 the area of grate or grates in square feet, which 
will give the number of tons of coal burned per heating season of 
240 days. 

A safe rule is that for each cubic foot of contents of building one 
pound of coal will be required for heating season of 240 days. 

The district steam heating companies usually estimate that 
each square foot of direct steam radiation will require 500 pounds 
of steam per season. 

To find size of coal storage room for a government building, 
ascertain maximum consumption of coal for entire heating season 
and allow 8 square feet of floor space per ton. 

To ascertain boiler horse-power for direct heating of a building 
in New York City or a similar climate, allow 100 boiler horse- 
power for each 1,000,000 cubic feet of contents for zero weather, 
and in average winter weather two-thirds of this will be the horse- 
power required. Between 40 and 50 per cent of the maximum 
will be the boiler horse-power required for the full heating season 
of 5700 hours. 

The boiler horse-power in Federal buildings with a heating and 
ventilating apparatus will average one boiler horse-power for each 
7000 cubic feet of contents. 

FAN SYSTEMS 

As a general rule the fan is used to supply air for ventilation 
alone, and the trunk main system of distribution of air is used, but 
in exceptional cases where the fan is used for heating as well as 
for ventilating the plenum chamber system is used for the distri- 
bution of the hot air. 

In other cases where requirements as to ventilation are not so 
exacting, but where it is desired to use fans for heating, sometimes 
on account of the construction of the building and again for rea- 
sons of control in climates of rapidly varying temperatures, the 
trunk main system is used; and if funds are available the air 
supply to the various rooms is automatically controlled by ther- 
mostats located in said rooms. 



HEATING AND VENTILATION 23 

Amount of air to be circulated. When air is used for ventila- 
tion alone, and the number of occupants of any given room is 
not known, three to five changes of air per hour are allowed in 
post-office work-rooms, court rooms, and carriers' swing rooms 
(depending upon the size, location, and opportunities for natural 
ventilation), and four air changes per hour in office rooms. When 
the number of occupants is known, 2000 cubic feet of air per hour 
is allowed for each occupant. 

When air is used for heating as well as for ventilation, the 
B.t.u. lost from the building are estimated exactly as heretofore 
given. The amount of air given above for ventilation is taken 
as the amount of air to be put into the room, and the tempera- 
ture at which the air must enter the room to heat it is estimated. 
If this temperature is above 125° F, more air is to be circulated, 
125° F. being taken as the maximum temperature of air entering 
a room, except in special cases. 

Kind and size of fans. The regular style of steel plate or multi- 
blade fans is used exclusively for plenum work. Disc fans are 
used only for ventilation without a heater, and then the total 
length of inlet and outlet pipe must be equivalent to not more 
than 100 feet of straight pipe of the diameter of the fan; and they 
are never required to work against any strong natural aspirating 
tendencies. 

In such cases the motor is usually provided with a reversing 
switch, or rocker arm, so that the fan may be easily reversed and 
made to supply fresh air or to exhaust air, as desired. Curved 
blade fans are generally specified, and required to be of a type 
that when running " backwards" will handle not less than 75 per 
cent of the amount of air they will handle when running " for- 
ward." 

Cone fans are used very seldom, and only where it is desired to 
reduce the power to a minimum at the expense of large ducts and 
much floor space. 

On exhaust ventilation, where owing to length of ducts or other 
reasons a disc fan is not wanted, the steel plate or multiblade fan 
is generally used, although a cone fan if it can discharge freely, 
is admirably adapted for this work. 

Capacity and power. The capacity of any fan may be expressed 
by the formula: 



24 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

C.F.M. = ADW, in which 
C.F.M. = cubic feet of air per minute. 
D = diameter of wheel in feet. 
N = number of revolutions per minute. 
A = a constant depending upon the kind of fan and 
the conditions under which it operates. 

The horse-power may be expressed by the formula: 

D 5 N 3 S 
B.H.P. = ^g- 5 , 

in which D and N are as given above and 

B.H.P. = horse-power applied to fan shaft; 

C = a constant depending on the kind of fan and the 

conditions under which it operates; 
S = a constant depending on the temperature of air 

handled by fan, which is 



i 



460 



'460 -M 

The values for A and C will be given for each of the following 
conditions for the various fans : 

Case I. For a fan used for plenum ventilation only, and with- 
out an air washer. 
Case II. Same as Case I, except that an air washer is used. 
Case III. For a fan used for both heating and ventilation, and 
without an air washer. 

Case IV. Same as Case III, except that an air washer is used. 
Case V. For a fan used for exhaust or forced ventilation, when 
no resistance is encountered but the duct system. 
Case VI. For a fan on free suction and discharge. 
Steel plate fans. Proportions are assumed to be as follows : 
Width periphery = 40 per cent diameter of wheel. 
Width housing = 57 per cent diameter of wheel. 
Diameter inlet in case = 62J per cent diameter of wheel. 
Eight blades, set radially, not curved. 
Multiblade fans. 

Width periphery = one-half diameter of wheel. 
Width casing = two-thirds diameter of wheel. 
Diameter inlet in case = diameter of wheel (practically). 



HEATING AND VENTILATION 



25 



Wheels above 9-inch diameter have 64 blades, curved slightly 
forward in the direction of rotation. 
Cone fans. 

Width periphery = 25 per cent diameter of wheel. 
Diameter inlet = 75 per cent diameter of wheel. 
In the following table are given the values of A and C to be sub- 
stituted in the general formulae given above for capacity and 
power of fans : 



CASE 
NUMBER 



I 

II 

III 

IV 

V 

VI 

I 

II 
III 

IV 

V 

VI 

I 

II 
III 

IV 
V 

VI 
V 

VI 

VI 



KIND OF FAN 



Steel plate 

Steel plate 

Steel plate 

Steel plate 

Steel plate 

Steel plate 

Multiblade.... 
Multiblade.... 
Multiblade.... 
Multiblade.... 
Multiblade.... 
Multiblade.... 
Cone type. . . . 
Cone type. . . . 
Cone type. . . . 
Cone type. . . . 
Cone type. . . . 
Cone type. . . . 
Propeller type 
Propeller type 
Disc 



A 



0.50 
0.42 
0.44 
0.40 
0.56 
0.62 
1.45 
1.34 
1.38 
1.10 
1.70 
1.95 
0.55 
0.48 
0.48 
0.45 
0.60 
0.73 
0.50 
0.70 
0.70 



12,000,000,000 

12,500,000,000 

12,500,000,000 

13,000,000,000 

11,500,000,000 

11,000,000,000 

1,700,000,000 

1,800,000,000 

1,750,000,000 

2,250,000,000 

1,500,000,000 

1,250,000,000 

13,000,000,000 

14,000,000,000 

14,000,000,000 

12,000,000,000 

11,500,000,000 

11,000,000,000 

33,000,000,000 

37,000,000,000 

42,500,000,000 



RATIO 
OF 
VELOCI- 
TIES 



The group " Propeller type" may be taken to cover the David- 
son, American Sirocco, or Sturtevant propeller fans. The group 
"Disc" includes all straight-blade disc fans having twelve or 
more wide blades. It does not, of course, cover the ordinary 
desk fan. 

The column headed "Ratio of velocities" in the table refers to 
the peripheral velocity of fan wheel divided by the mean velocity 
of air in the heating coils. The ratios given are maintained as 
nearly as practicable. 



26 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



Speed of fans. Steel plate fans are run at a peripheral speed 
of 3000 to 4000 feet per minute, except when an air washer is 
used, when the speed must be about 4500 feet per minute. 

Multiblade fans are run at a peripheral speed of 2200 to 2500 
feet per minute, and about 3000 feet when an air washer is used. 

Cone fans are run at a peripheral speed of 3600 to 4600 feet per 
minute, and at least 5000 feet when an air washer is used. 

Propeller type fans to operate at a peripheral speed of 2500 to 
6500 per minute and disc fans from 3000 to 8000 feet per minute. 

The formulae for power are based on 8-blade wheels about 6 
feet diameter; sirocco wheels 4 feet diameter; cone wheels 6 feet 
diameter; and disc and propeller wheels 4 feet diameter. The 
horse-power should be increased about 5 per cent for each foot in 
diameter less than these diameters, to cover decrease in efficiency. 
No decrease in power for larger wheels. 

Heaters. Heaters used with fans are usually of cast-iron base, 
miter type, with wrought-iron pipe surface, or the all cast-iron 
heaters, such as the "Vento." 

The data published by the American Radiator Co. on tem- 
perature rise and condensation in Vento Heaters has been found 
to be thoroughly reliable. The heaters are designed on this 
basis and wrought iron heaters when used are required to have 
the same heating surface and same free area as would be required 
for "Vento." 

These data are given hereinafter. 

Friction. The friction in pipe coils on 2f-inch centers is as 
follows : 



AIR VELOC- 
ITY FEET 
PER MINUTE 


4 ROWS 


8 ROWS 


12 ROWS 


16 ROWS 


20 ROWS 


24 rows 


600 


0.04 


0.06 


0.09 


0.12 


0.14 


0.15 


800 


0.06 


0.10 


0.15 


0.19 


0.23 


0.26 


1,000 


0.09 


0.15 


0.21 


0.30 


0.37 


0.41 


1,200 


0.12 


0.21 


0.31 


0.43 


0.50 


0.58 


1,400 


0.17 


0.30 


0.45 


0.60 


0.75 


0.90 



Friction is inches of water, and for any other velocities may be 
taken as varying as the square of the velocity. 

The free air space with pipes on 2f-inch center = total number 
lineal feet of pipe in the heater, divided by the number of pipes 
deep, divided by 8.4. 



HEATING AND VENTILATION 



27 



All the above is for 1-inch diameter pipes. One and a quarter 
inch pipes at same air velocity will give practically the same 
B.t.u. per square foot per hour. 

Sections should be tapped as follows: 



POUNDS STEAM PER 
HOUR PER SECTION 


STEAM TAP 


DRIP TAP 


BLEEDER TAP 




inches 


inches 


inches 


80 


2 


li 


3 

4 


160 


n 


11 


3 

4 


320 


3 


2 


U 


480 


3| 


21 


li 


960 


4 


2* 


H 



Vento heaters. The free area in square feet = the total number 
of square feet of heating surface divided by the number of sections 
and this quotient divided by 17.6 for standard sections and by 
12.1 for the narrow type sections. Long spacing (5f-inch cen- 
ters) increases the free area 18 per cent over the standard spacing, 
and short spacing (4f-inch centers) decreases it to 85 per cent of 
the standard. 

The following table gives the friction in inches of water for 
various depths of coils and various velocities. 





REGULAR SECTION 


NARROW SECTION 


VELOCITY FEET 










PER MINUTE 


One Section 


Add for Each Ad- 
ditional Section 


Two Sections 


Add for Each Ad- 
ditional Section 


600 


0.022 


0.018 


0.028 


0.015 


700 


0.030 


0.025 


0.037 


0.020 


800 


0.040 


0.032 


0.048 


0.027 


900 


0.051 


0.040 


0.061 


0.034 


1,000 


0.063 


0.050 


0.075 


0.042 


1,100 


0.076 


0.060 


0.090 


0.050 


1,200 


0.090 


0.072 


0.107 


0.060 


1,300 


0.105 


0.085 


0.126 


0.070 


1,400 


0.122 


0.102 


0.147 


0.082 


1,500 


0.140 


0.112 


0.170 


0.093 



Sections are on standard spacing (5-inch centers) . 

Velocity is volume of air measured at 70° F. 

Standard " Vento" tappings are 2 J inches, but the feed sections 
can be tapped 3 inches or 3 J inches. Use tapping schedule given 
for wrought-iron coils. Bush the returns to one-half diameter of 



28 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

steam tap plus one pipe size. Not over 480 pounds steam per 
hour is condensed in one group. 

One-half or three-quarter inch air valves are installed at each 
end of each group about 8 inches from bottom of sections. 

Use the "standard" spacing (5-inch center to center) unless 
otherwise instructed. The " narrow" spacing, which is 4f-inch 
centers, and the "wide" spacing, which is 5|-inch centers, are not 
to be used except under special conditions. 

The free area for standard spacing is 44 per cent of the area of 
face ; the narrow 37 per cent ; and the wide 52 per cent . 

The 40-inch high 9|-inch deep section contains 10.75 square feet. 
The 50-inch high 9|-inch deep section contains 13.50 square feet. 
The 60-inch high 9£-inch deep section contains 16.00 square feet. 
The 40-inch high 6|-inch deep section contains 7.50 square feet. 
The 50-inch high 6f-inch deep section contains 9.50 square feet. 
The 60-inch high 6f-inch deep section contains 11.00 square feet. 

For example, if a 60-inch high heater is desired with 22 square 
feet free area: 22 -r- 44 per cent = 50 square feet gross area -f- 
5 feet (high) = 10 feet = 120 inches wide -f- 5 = 24 sections 
wide. 

After size of heater is found by the free area method, check same 
by the B.t.u. method by estimating the total B.t.u. required and 
dividing same by the condensation; the B.t.u. per square foot per 
hour being taken from the tables and corrected for difference in 
temperature (same as outlined for correction of temperature rise) . 

Hot water. With water at a mean temperature of 180° F. the 
rise in temperature with wrought-iron coils and the B.t.u. trans- 
mitted are about 75 per cent of what they would be with steam 
at 227° when the velocity of air leaving the coil, number of pipes 
deep, spacing, etc., are the same. 

To get the same rise in temperature with incoming air same 
temperature, same sections, same depth, etc., the velocity of air 
will be 40 per cent of what would be estimated for steam at 227°. 

With hot water, forced circulation must be used in fan blast 
coils. 

If high-pressure steam is used, the rise in temperature and con- 
densation are estimated on the principle that these quantities are 
in proportion to the difference in temperatures of steam and en- 
tering air. 



HEATING AND VENTILATION 



29 



FRICTION OF AIR THROUGH VENTO HEATERS 

Friction Loss — In Inches of Water — Due to Air Passing through 

Vento Stacks. (Measured at 70°) 

Regular Section — 4h 5 an d 5%-Inches Spacing 



fa 

w 
fa 

as 

S H 


fa fa 
on K 
fa « 
O g 

52 

03 


1 STACK 


2 STACKS 


3 STACKS 


4 STACKS 


5 STACKS 


6 STACKS 


7 STACKS 


8 STACKS 




4| 

5 

5f 


0.022 
0.021 
0.019 


0.043 
0.040 
0.034 


0.063 
0.058 
0.049 


0.084 
0.076 
0.064 


0.105 
0.094 
0.079 


0.126 
0.112 
0.094 


0.147 
0.130 
0.109 




600 


0.149 

0.124 


700 


4f 
5 

51 


0.031 
0.028 
0.025 


0.059 
0.054 
0.046 


0.087 
0.079 
0.066 


0.115 
0.105 
0.087 


0.143 
0.130 
0.108 


0.172 
0.155 
0.128 


0.200 
0.180 
0.149 


0.205 
0.170 




45 

5 

51 


0.040 
0.037 
0.033 


0.077 
0.070 
0.060 


0.114 
0.103 
0.087 


0.150 
0.135 
0.114 


0.187 
0.167 
0.140 


0.224 
0.200 
0.167 


0.259 
0.232 
0.194 




800 


0.265 
0.221 




41 

5 

51 


0.051 
0.047 
0.042 


0.097 
0.088 
0.076 


0.144 
0.129 
0.110 


0.190 
0.170 
0.144 


0.237 
0.211 
0.178 


0.283 
0.252 
0.212 


0.329 
0.293 
0.246 




900 


0.335 
0.280 




4.5 

*8 

5 

08 

4.5 
*8 

5 
is 


0.063 
0.059 
0.052 


0.120 
0.109 
0.094 


0.178 
0.160 
0.136 


0.235 
0.211 

0.178 


0.293 
0.262 
0.220 


0.350 
0.313 
0.262 


0.407 
0.364 
0.304 




1000 


0.415 
0.346 




0.076 
0.071 
0.062 


0.145 
0.132 
0.113 


0.214 
0.193 
0.164 


0.284 
0.255 
0.215 


0.353 
0.316 
0.265 


0.422 
0.377 
0.316 


0.491 
0.438 
0.367 




1100 


0.501 
0.418 




45 
*8 

5 

°8 


0.090 
0.084 
0.074 


0.172 
0.157 
0.134 


0.255 
0.230 
0.195 


0.337 
0.303 
0.255 


0.420 
0.376 
0.316 


0.502 
0.449 
0.376 


0.584 
0.522 
0.437 




1200 


0.596 
0.497 




45 

*8 

5 

"8 


0.105 
0.099 
0.087 


0.202 
0.185 
0.158 


0.299 
0.271 
0.229 


0.396 
0.356 
0.300 


0.493 
0.442 
0.371 


0.590 
0.528 
0.442 


0.687 
0.614 
0.513 




1300 


0.701 
0.584 


1400 


45 

*8 

5 

5! 


0.122 
0.115 
0.101 


0.234 
0.214 
0.183 


0.347 
0.314 
0.266 


0.459 
0.414 
0.348 


0.572 
0.513 
0.430 


0.684 
0.612 
0.512 


0.796 
0.712 
0.595 


0.813 
0.677 




4f 

5 

5| 


0.140 
0.132 
0.116 


0.269 
0.246 
0.210 


0."398 
0.360 
0.305 


0.527 
0.474 
0.399 


0.656 
0.588 
0.493 


0.785 
0.702 
0.587 


0.914 
0.816 
0.682 




1500 


0.932 
0.776 




45 

*8 

5 

51 


0.160 
0.150 
0.132 


0.306 
0.280 
0.239 


0.453 
0.410 
0.347 


0.600 
0.540 
0.454 


0.746 
0.i670 
0.561 


0.893 
0.800 
0.668 


1.040 
0.930 
0.776 




1600 


1.060 
0.883 




4f 

5 

51 


0.180 
0.169 
0.149 


0.346 
0.316 
0.270 


0.512 
0.463 
0.391 


0.677 
0.609 
0.512 


0.843 
0.756 
0.634 


1.009 
0.903 
0.755 


1.174 
1.049 
0.876 




1700 


1.197 
0.997 




45 
5 

08 


0.202 
0.190 
0.167 


0.387 
0.354 
0.303 


0.573 
0.518 
0.439 


0.759 
0.683 
0.575 


0.944 
0.848 
0.710 


1.130 
1.012 
0.846 


1.316 
1.177 
0.982 




1800 


1.342 
1.118 



30 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



FRICTION OF AIR THROUGH VENTO HEATERS 

Friction Loss — In Inches of Water— Due to Air Passing through 

Vento Stacks. (Measured at 70°) 

Narrow Section — 4h 5 and 5f Inches Spacing 



W 

►.a 

o« 


O CO 

as W 
O 5 

O 05 

PS 
05 

5 

08 

4.5 

^8 

5 

^8 


1 

STACK 


2 

STACKS 


3 

STACKS 


4 

STACKS 


5 

STACKS 


6 

STACKS 


7 

STACKS 


8 

STACKS 


9 

STACKS 


10 

STACKS 




0.018 
0.017 

0.015 


0.032 
0.030 
0.026 


0.047 
0.042 
0.036 


0.061 
0.055 

0.047 


0.076 
0.067 
0.058 


0.090 
0.080 
0.069 


0.104 
0.093 
0.079 


0.119 
0.105 
0.090 






600 


0.118 

0.101 


0.131 

0.111 




0.025 
0.023 
0.021 


0.045 
0.040 
0.036 


0.065 
0.057 
0.050 


0.085 
0.074 
0.065 


0.105 
0.092 
0.080 


124 
0.109 

0.095 


0.144 
0.126 
0.109 


0.164 
0.143 

0.124 

0.212 
0.187 
0.161 




700 


0.160 
0.139 


0.178 
0.153 




4.5 

*8 

5 

51 

4f 
5 

08 


0.032 
0.030 

0.027 


0.058 
0.052 
0.046 


0.083 
0.074 
0.065 


0.109 
0.097 
0.084 


0.135 
0.120 
0.103 


0.160 
0.142 
0.123 


0.186 
0.165 
0.142 






800 


0.210 

0.180 


0.232 
0.199 




0.041 
0.038 
0.034 


0.073 
0.066 
0.058 


0.106 
0.095 
0.082 


0.138 
0.123 
0.107 


0.171 
0.151 
0.131 


0.203 
0.180 
0.155 


0.236 
0.208 
0.179 


0.268 
0.237 
0.213 






900 


0.265 

0.228 


0.293 
0.252 




4.5 
*8 

5 

08 


0.050 
0.047 
0.042 


0.090 
0.082 
0.072 


0.131 
0.117 
0.102 


0.171 
0.152 
0.132 


0.211 
0.187 
0.162 


0.251 
0.223 
0.192 


0.292 
0.258 
0.221 


0.332 
0.293 
0.251 






1000 


0.328 
0.281 


0.364 
0.311 




4.5 

*8 

5 

08 


0.061 
0.057 
0.051 


0.109 
0.099 
0.087 


0.158 
0.141 
0.123 


0.207 
0.184 
0.159 


0.255 
0.226 
0.195 


0.304 
0.269 
0.232 


0.352 
0.311 
0.258 


0.401 
0.354 
0.304 




1100 


0.396 
0.400 


0.438 
0.376 


1200 


41 

5 

08 

45 
*8 

5 

08 


0.072 
0.067 
0.061 


0.130 
0.118 
0.104 


0.188 
0.169 
0.147 


0.246 
0.219 
0.190 


0.303 
0.269 
0.233 


0.361 
0.320 

0.276 


0.419 
0.371 
0.318 


0.477 
0.422 
0.361 


0.472 
0.404 


0.522 
0.447 




0.085 
0.079 
0.072 

0.098 
0.092 
0.083 


0.153 
0.139 
0.122 


0.221 
0.198 
0.173 


0.289 
0.257 
0.223 


0.356 
0.317 
0.273 


0.424 
0.376 
0.324 


0.492 
0.436 
0.374 


0.560 
0.495 

0.424 






1300 


0.554 

0.474 


0.614 
0.525 




45 

5 

5f 


0.177 
0.161 
0.141 


0.256 
0.230 
0.200 


0.335 
0.299 
0.258 


0.413 
0.368 
0.317 


0.492 
0.437 
0.375 


0.571 
0.506 

0.433 

0.655 
0.579 
0.497 


0.650 
0.574 
0.492 






1400 


0.643 
0.550 


0.712 
0.609 




4f 
5 

5! 


0.112 
0.105 

0.095 


0.202 
0.184 
0.162 


0.293 
0.263 
0.229 


0.383 
0.342 

0.296 


0.474 
0.421 
0.363 


0.564 
0.500 
0.430 


0.745 
0.658 
0.564 






1500 


0.737 
0.631 


0.816 
0.698 




45 

*8 

5 

08 


0.128 
0.120 
0.108 


0.231 
0.210 
0.184 


0.334 
0.300 
0.261 


0.437 
0.390 
0.337 


0.539 
0.480 
0.413 


0.642 
0.570 
0.490 


0.745 
0.660 
0.566 


0.848 
0.750 
0.642 






1600 


0.840 
0.718 


0.930 
0.795 




45 
*8 

5 

5f 


0.145 
0.136 
0.122 


0.261 
0.237 
0.208 


0.377 
0.339 
0.204 


0.493 
0.440 
0.381 


0.610 
0.542 

0.467 


0.726 
0.644 
0.553 


0.842 
0.745 
0.639 


0.958 
0.847 
0.725 






1700 


0.948 
0.812 


1.049 
0.898 




4f 

5 

5| 


0.162 
0.152 
0.137 


0.292 
0.266 
0.234 


0.422 
0.380 
0.330 


0.552 
0.494 
0.427 


0.683 
0.608 
0.523 


0.813 
0.722 
0.620 


0.943 
0.835 
0.716 


1.073 
0.949 
0.813 






1800 


1.063 
0.909 


1.177 
1.006 



NARROW SECTION— RATINGS AND FREE AREAS 

40-Inch Section — 7.5 Square Feet. Height 41-£t inch. Width tff inches 





O H 

* 5 

H P 
fa CO 

O 

H 5 

K Eh 

<! < 
P H 


*EQUIVALENT IN 
LINEAL FEET 1-INCH 
PIPE 


5f INCH CENTERS 
OF SECTIONS 


5 INCH CENTERS 
OF SECTIONS 


4| INCH CENTERS 
OF SECTIONS 


m 


NUMBER OF SEC- 


52% of Face 


Standard 44% 
of Face 


37% of Face 


Eh 

a 

O 


TIONS IN STACK 


Net Air 

Space in 

Square 

feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Space in 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Spacein 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


►H 
< 
P 

Eh 
O 

< 


7 


52.5 


158 


5.12 


38 


4.34 


35 


3.67 


32 




8 


60.0 


180 


5.85 


43 


4.96 


40 


4.20 


37 




9 


67.5 


203 


6.57 


48 


5.58 


45 


4.72 


42 




10 


75.0 


225 


7.29 


54 


6.20 


50 


5.25 


46 




11 


82.5 


248 


8.02 


59 


6.82 


55 


5.77 


51 


HP 


12 


90.0 


270 


8.74 


65 


7.44 


60 


6.30 


55 


03 £ 


13 


97.5 


293 


9.47 


70 


8.06 


65 


6.82 


60 


-p 

a a 


14 


105.0 


315 


10.19 


75 


8.68 


70 


7.35 


65 


■p a 

**-' a 


15 


112.5 


338 


10.91 


81 


9.30 


75 


7.87 


69 


CO 02 


16 


120.0 


360 


11.64 


86 


9.92 


80 


8.40 


74 


(-1 • 

CO +» 


17 


127.5 


383 


12.36 


91 


10.54 


85 


8.92 


79 


i« 


18 


135.0 


405 


13.09 


97 


11.16 


90 


9.45 


83 


CM P. 

oo 02 


19 


142.5 


428 


13.82 


102 


11.78 


95 


9.97 


88 


20 


150.0 


450 


14.54 


108 


12.40 


100 


10.50 


92 


OS 


21 


157.5 


473 


15.26 


113 


13.02 


105 


11.02 


97 




22 


165.0 


495 


15.98 


118 


13.64 


110 


11.55 


102 




23 


172.5 


518 


16.71 


124 


14.26 


115 


12.07 


106 




24 


180.0 


540 


17.43 


129 


14.88 


120 


12.60 


111 





50-Inch Section — 9.5 Square Feet. Height 50%% inches. Width 6"f inches 





5| INCH CENTERS 


5 INCH CENTERS 


4f INCH CENTERS 




7 


66.5 


200 


6.35 


38 


5.37 


35 


4.55 


32 




8 


76.0 


228 


7.25 


43 


6.14 


40 


5.20 


37 




9 


85.5 


257 


8.15 


48 


6.91 


45 


5.85 


42 




10 


95.0 


285 


9.05 


54 


7.68 


50 


6.50 


46 




11 


104.5 


314 


9.95 


59 


8.45 


55 


7.15 


51 


H-3 
r^H 

M 


12 


114.0 


342 


10.85 


65 


9.22 


60 


7.80 


55 


3 P 


13 


123.5 


371 


.11.75 


70 


9.99 


65 


8.45 


60 




14 


133.0 


399 


12.65 


75 


10.76 


70 


9.10 


65 


+5 a 

"- a 


15 


142.5 


428 


13.55 


81 


11.53 


75 


9.75 


69 


CJ3 
m to 


16 


152.0 


456 


14.45 


86 


12.30 


80 


10.40 


74 


CD -P 


17 


161.5 


485 


15.35 


91 


13.07 


• 85 


11.05 


79 


s- 


18 


171.0 


513 


16.25 


97 


13.84 


90 


11.70 


83 


Sa 


19 


180.5 


542 


17.15 


102 


14.59 


95 


12.35 


88 


oo CO 


20 


190.0 


570 


18.05 


108 


15.36 


100 


13.00 


92 


C5 


21 


199.5 


599 


18.95 


113 


16.13 


105 


13.65 


97 




22 


209.0 


627 


19.85 


118 


16.90 


110 


14.30 


102 




23 


218.5 


656 


20.75 


124 


17.67 


115 


14.95 


106 




24 


228.0 


684 


21.65 


129 


18 ..44 


120 


15.60 


111 





31 



32 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



NARROW SECTION— Continued 



60-Inch Sech 


on — 11 Square Feet. 


Height 60^% 


inches 


. Width £f inches 




O H 
o 
«! 

H K 

& a 

a w 

03 


'equivalent in 
lineal feet 1-inch 

PIPE 


5f INCH CENTERS 
OF SECTIONS 


5 INCH CENTERS 
OF SECTIONS 


4| INCH CENTERS 
OF SECTIONS 


(0 


NUMBER OF SEC- 


52% of Face 


Standard 44% 
of Face 


37% of Face 


H 

X 
O 

3 


TIONS IN STACK 


Net Air 

Spacein 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Spacein 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Spacein 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


& 

H 

< 


7 


77.0 


231 


7.62 


38 


6.45 


35 


5.47 


32 




8 


88.0 


264 


8.70 


43 


7.37 


40 


6.25 


37 




9 


99.0 


297 


9.77 


48 


8.29 


45 


7.03 


42 




10 


110.0 


330 


10.85 


54 


9.21 


50 


7.81 


46 




11 


121.0 


363 


11.93 


59 


10.13 


55 


8.59 


51 


■+3 
fcfi 


12 


132.0 


396 


13.00 


65 


11.05 


60 


9.37 


55 




13 


143.0 


429 


14.08 


70 


11.97 


65 


10.15 


60 




14 


154.0 


462 


15.15 


75 


12.89 


70 


10.93 


65 


■is Ot 


15 


165.0 


495 


16.23 


81 


13.81 


75 


11.71 


69 


<B TO 


16 


176.0 


528 


17.31 


86 


14.73 


80 


12.49 


74 




17 


187.0 


561 


18.39 


91 


15.65 


85 


13.27 


79 


& . 

ri O* 

CO to 


18 


198.0 


594 


19.46 


97 


16.57 


90 


14.05 


83 




19 


209.0 


627 


20.54 


102 


17.50 


95 


14.83 


88 


06 tn 


20 


220.0 


660 


21.62 


108 


18.42 


100 


15.61 


92 


OS 


21 


231.0 


693 


22.70 


113 


19.34 


105 


16.39 


97 




22 


242.0 


726 


23.78 


118 


20.26 


110 


17.17 


102 




23 


253.0 


759 


24.85 


124 


21.18 


115 


17.95 


106 




24 


264.0 


792 


25.93 


129 


22.10 


120 


18.73 


111 





INote. — Add to the width of stack 2| inches for staggering of stacks. 

*Note. — The actual length of one-inch pipe per square foot of outside 
surface is 2.9 lineal feet but is nominally figured at 3 lineal feet, as shown 
in the third column of above table. 



REGULAR SECTION— RATINGS AND FREE AREAS 

30-Inch Section {Steam only) — 8 Square Feet. Height 30 inches. Width 

9k inches 



m 

Z 
o 


O H 
O 

< 

fa to 


5 H 


5| INCH CENTERS 
OF SECTIONS 


5 INCH CENTERS 
OP SECTIONS 


4| INCH CENTERS 
OF SECTIONS 


4 INCH CENTERS 
OF SECTIONS 


m 


H 
03 


52% of Face 


Standard 44% 
of Face 


37% of Face 


24% of Face 


a 
o 
i-t 


O w 

o a 


a H 
§a 

CO 


> >J 
m ■«! 

e* a a 

a j e, 
* 


Net Air 

Space in 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Space in 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Spacein 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Spacein 

Square 

Feet 


Width 
of Stack 

in 
Inches 


►J 
< 
a 

O 
< 


7 


56 


168 


3.81 


38 


3.22 


35 


2.73 


32 


1.79 


28 




8 


64 


192 


4.35 


43 


3.68 


40 


3.12 


37 


2.04 


32 




9 


72 


216 


4.88 


48 


4.14 


45 


3.52 


42 


2.30 


36 




10 


80 


240 


5.42 


54 


4.60 


50 


3.90 


46 


2.25 


40 




11 


88 


264 


5.96 


59 


5.06 


55 


4.29 


51 


2.81 


44 


-*3 


12 


96 


288 


6.50 


65 


5.52 


60 


4.68 


55 


3.06 


48 


"S'l 


13 


104 


312 


7.04 


70 


5.98 


65 


5.07 


60 


3.32 


52 


% M 


14 


112 


336 


7.57 


75 


6.44 


70 


5.46 


65 


3.57 


56 


* ft 


15 


120 


360 


8.11 


81 


6.90 


75 


5.85 


69 


3.83 


60 


O"^ 


16 


128 


384 


8.65 


86 


7.36 


80 


6.24 


74 


4.08 


64 


(-1 ^ 


17 


136 


408 


9.19 


91 


7.82 


85 


6.63 


79 


4.34 


68 


2. . 


18 


144 


432 


9.73 


97 


8.28 


90 


7.02 


83 


4.59 


72 


— ' © 

° a 


19 


152 


456 


10.27 


102 


8.75 


95 


7.41 


88 


4.85 


76 


20 


160 


480 


10.81 


108 


9.21 


100 


7.80 


92 


5.11 


80 


OS 


21 


168 


504 


11.35 


113 


9.67 


105 


8.19 


97 


5.36 


84 




22 


176 


528 


11.89 


118 


10.13 


110 


8.58 


102 


5.62 


88 




23 


184 


552 


12.42 


124 


10.59 


115 


8.97 


106 


5.87 


92 




24 


192 


576 


12.96 


129 


11.05 


120 


9.36 


111 


6.13 


96 





40-Inch Section (Steam or Water) — 10.75 Square Feet. 



Height 41-£t inches. 













tuuo a t 


f iiucnt 


,s 












5f INCH CENTERS 


5 INCH CENTERS 


4| INCH CENTERS 


4 INCH CENTERS 




7 


75.25 


226 


5.12 


38 


4.34 


35 


3.67 


32 


2.45 


28 




8 


86.00 


258 


5.85 


43 


4.96 


40 


4.20 


37 


2.80 


32 




9 


96.75 


290 


6.57 


48 


5.58 


45 


4.72 


42 


3.15 


36 




10 


107.50 


323 


7.29 


54 


6.20 


50 


5.25 


46 


3.50 


40 




11 


118.25 


355 


8.02 


59 


6.82 


55 


5.77 


51 


3.85 


44 


+3 


12 


129.00 


387 


8.74 


65 


7.44 


60 


6.30 


55 


4.20 


48 


tt 


13 


139.75 


419 


9.47 


70 


8.06 


65 


6.82 


60 


4.55 


52 


t M 


14 


150.50 


452 


10.19 


75 


8.68 


70 


7.35 


65 


4.90 


56 


fl p 


15 


161.25 


484 


10.91 


81 


9.30 


75 


7.87 


69 


5.25 


60 


6*^3 


16 


172.00 


516 


11.64 


86 


9.92 


80 


8.40 


74 


5.60 


64 


Si -i 


17 


182.75 


548 


12.36 


91 


10.54 


85 


8.92 


79 


5.95 


68 


. a 1 


18 


193.50 


581 


13.09 


97 


11.16 


90 


9.45 


83 


6.30 


72 


— ' <B 


19 


204.25 


613 


13.82 


102 


11.78 


95 


9.97 


88 


6.65 


76 


od aj 


20 


215.00 


645 


14.54 


108 


12.40 


100 


10.50 


92 


7.00 


80 


OS 


21 


225.75 


677 


15.26 


113 


13.02 


105 


11.02 


97 


7.35 


84 




22 


236.50 


710 


15.98 


118 


13.64 


110 


11.55 


102 


7.70 


88 




23 


247.25 


742 


16.71 


124 


14.26 


115 


12.07 


106 


8.05 


92 




24 


258.00 


774 


17.43 


129 


14.88 


120 


12.60 


111 


8.40 


96 





33 



34 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



REGULAR SECTION— Continued 

50-Inch Section {Steam or Water) — 13.5 Square Feet. 

Width 9k inches 



Height 50ff inches. 



aa 

o 


Ed 

O p) 

O 
«i 

H « 


*EQUIVALENT IN 
LINEAL FEET 1-INCH 
PIPE 


5f INCH CENTERS 
OB SFCTIONS 


5 INCH CENTERS 
OF SECTIONS 


4f INCH CENTERS 
OF SECTIONS 


4 INCH CENTERS 
OF SECTIONS 


in 


o 
w 
to 
ft 


52% of Face 


Standard 44% 
of Face 


37% of Face 


24% of Face 


w 
o 

3 


o \4 




Net Air 

Space in 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Space in 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Space in 

Square 

Feet 


Width 
of Stack 

in 
Inches 


Net Air 

Space in 

Square 

Beet 


Width 
of Stack 

in 
Inches 


< 

E* 
O 

■< 


7 


94.5 


284 


6.35 


38 


5.37 


35 


4.55 


32 






8 


108.0 


324 


7.25 


43 


6.14 


40 


5.20 


37 






9 


121.5 


365 


8.15 


48 


6.91 


45 


5.85 


42 






10 


135.0 


405 


9.05 


54 


7.68 


50 


6.50 


46 


a 




11 


148.5 


446 


9.95 


59 


8.45 


55 


7.15 


51 


T3 


+= 

JS 


12 


162.0 


486 


10.85 


65 


9.22 


60 


7.80 


55 


3© 

JKco 




13 


175.5 


527 


11.75 


70 


9.99 


65 


8.45 


60 


14 


189.0 


567 


12.65 


75 


10.76 


70 


9.10 


•65 


03 <D 


-p 0, 


15 


202.5 


608 


13.55 


81 


11.53 


75 


9.75 


69 


0^ 


crlS 


16 


216.0 


648 


14.45 


86 


12.30 


80 


10.40 


74 


c3 03 
O S-i 

03 * 




17 


229.5 


689 


15.35 


91 


13.07 


85 


11.05 


79 


9"^ 

O 0) 


■ C 
m 03 


18 


243.0 


729 


16.25 


97 


13.84 


90 


11.70 


83 


"43 « 




19 


256.5 


770 


17.15 


102 


14.59 


95 


12.35 


88 




00 03 


20 


270.0 


810 


18.05 


108 


15.36 


100 


13.00 


92 


.2 


o 


21 


283.5 


851 


18.95 


113 


16.13 


105 


13.65 


97 


o 




22 


297.0 


891 


19.85 


118 


16.90 


110 


14.30 


102 






23 


310.5 


932 


20.75 


124 


17.67 


115 


14.95 


106 






24 


324.0 


972 


21.65 


129 


18.44 


120 


15.60 


111 







f Note — Add to the width of stack 2\ inches for staggering of stacks 
— except 4 inch centers not staggered. 

* Note. — The actual length of one-inch pipe per square foot of outside 
surface is 2.9 lineal feet but is nominally figured at 3 lineal feet, as shown 
in the third column of above tables. 



REGULAR SECTION— RATINGS AND FREE AREAS 

60-Inch Section {Steam or Water) — 16 Square Feet. Height 60j% inches, 

Width 9h inches. 





O f£\ 


25 S 


5| INCH CENTERS 


5 INCH CENTERS 


4f INCH CENTERS 






< 




OF SECTIONS 


OF SECTIONS 


OF SECTIONS 


00 


NUMBER OF SEC- 


52% of Face 


Standard 44% 
of Face 


37% of Face 


X 

o 


TIONS IN STACK 


< < 

£0 


M <! 

a ~ fc 
* 


Net Air 

Space in 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Space in 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


Net Air 

Space in 

Square 

Feet 


tWidth 
of Stack 

in 
Inches 


< 

U 

< 


7 


112.0 


336 


7.62 


38 


6.45 


35 


5.47 


32 




8 


128.0 


384 


8.70 


43 


7.37 


40 


6.25 


37 




9 


144.0 


432 


9.77 


48 


8.29 


45 


7.03 


42 




10 


160.0 


480 


10.85 


54 


9.21 


50 


7.81 


46 




11 


176.0 


528 


11.93 


59 


10.13 


55 


8.59 


51 




12 


192.0 


576 


13.00 


65 


11.05 


60 


9.37 


55 


— i.SP 

c3'S 
c3 M 


13 


208.0 


624 


14.08 


70 


11.97 


65 


10.15 


60 


14 


224.0 


672 


15.15 


75 


12.89 


70 


10.93 


65 


+>% 


15 


240.0 


720 


16.23 


81 


13.81 


75 


11.71 


69 


o"'J5 


16 


256.0 


768 


17.31 


86 


14.73 


80 


12.49 


74 




17 


272.0 


816 


18.39 


91 


15.65 


85 


13.27 


79 


£5f 


18 


288.0 


864 


19.46 


97 


16.57 


90 


14.05 


83 


00 TO 


19 


304.0 


912 


20.54 


102 


17.50 


95 


14.83 


88 


20 


320.0 


960 


21.62 


108 


18.42 


100 


15.61 


92 


03 


21 


336.0 


1008 


22.70 


113 


19.34 


105 


16.39 


97 




22 


352.0 


1056 


23.78 


118 


20.26 


110 


17.17 


102 




23 


368.0 


1104 


24.85 


124 


21.18 


115 


17.95 


106 




24 


384.0 


1152 


25.93 


129 


22.10 


120 


18.73 


111 





72-Inch Section (For Steam or Water) — 19 Square Feet. Height 72 inches. 











It £7g 111 


lslWi> 












5| INCH CENTERS 


5 INCH CENTERS 


4f INCH CENTERS 




7 


133 


399 


9.14 


38 


7.74 


35 


6.56 


32 




8 


152 


456 


10.44 


43 


8.85 


40 


7.50 


37 




9 


171 


513 


11.72 


48 


9.95 


45 


8.45 


42 




10 


190 


570 


13.03 


54 


11.04 


50 


9.37 


46 




11 


209 


627 


14.31 


59 


12.17 


55 


10.30 


51 


-1-3 


12 


228 


684 


15.60 


65 


13.27 


60 


11.25 


55 


"*"§ 


13 


247 


741 


16.90 


70 


14.35 


65 


12.18 


60 


O M 


14 


266 


798 


18.19 


75 


15.46 


70 


13.11 


65 


-li — 


15 


285 


855 


19.49 


81 


16.58 


75 


14.06 


69 


ctS 


16 


304 


912 


20.78 


86 


17.70 


80 


14.99 


74 


& 


17 


323 


969 


22.07 


91 


18.78 


85 


15.92 


79 


rA C 


18 


342 


1026 


23.34 


97 


19.88 


90 


16.86 


83 




19 


361 


1083 


24.64 


102 


21.00 


95 


17.80 


88 


OO GO 


20 


380 


1140 


25.95 


108 


22.10 


100 


18.73 


92 


OS 


21 


399 


1197 


27.25 


113 


23.20 


105 


19.67 


97 




22 


418 


1254 


28.52 


118 


24.31 


110 


20.60 


102 




23 


437 


1311 


29.80 


124 


25.40 


115 


21.54 


106 




24 


456 


1368 


31.10 


129 


26.50 


120 


22.47 


111 





* f See notes bottom of previous page. 

Note. — 60-Inch Sections can be assembled on 4-inch centers. 

35 



36 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

CONDENSATION AND TEMPERATURE TABLES, ETC. 

The tables presented on the following pages are the result of 
the most thorough test ever applied to blast heaters. The data 
represent nearly 50,000 calculations. The results of the tests 
on temperatures and condensations were incorporated in a mathe- 
matical deduction which properly represents the theory of con- 
vection of heat. 

The tests covered a range of velocities of air through the heater 
from 50 feet per minute up to 2500 feet per minute. In these 
tests velocitieis were derived from actual air measurements with 
a manometer, and these velocities checked within an average of 2 
per cent with the velocities calculated from the amounts of con- 
densation weighed. 

The data presented cover tests of six different Vento Heaters 
with steam at 5 pounds gauge pressure, and air entering at vari- 
ous temperatures below zero, at zero, and above zero. Data are 
also given of the performances of the heaters with steam at 30 
pounds pressure, and with hot water circulation. 





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HEATING AND VENTILATION 51 

Prime movers. When engines are used, which is seldom, they 
are vertical, single or double-cylinder. Engines are direct-con- 
nected where possible and are provided with throttling governor. 

Motors, if direct-current, are direct-connected when speed of 
fan is 300 turns per minute or more. If current is alternating, 
the motor is belted to the fan or connected by a silent chain drive. 

Flange or flexible couplings are used for direct-connecting 
motors and engines. 

Steam and return piping. 



V 



ILW 2 
D= < l/-^p , m which 



D = diameter of pipe in inches. 

L = length of pipe in feet (one way) . 

W = pounds of steam per minute. 

P = loss of pressure, usually one pound per 300 feet. 

K — a constant as follows : 

Diameters (inches) 1 2 3 4 5 6 7 8 

K= 104 140 160 169 173 180 183 187 

For steam above 30 pounds pressure pipe is made half the 
diameter given by the formula, and for pressures of 10 to 30 
pounds main is made two-thirds that given. 

Return main one-half diameter of steam main, and make it 
"wet." 

Place the bottom of coil as high as possible above water line 
in boiler, pump governor, or trap; never less than 18 inches and 
preferably 24 inches. 

AIR DISTRIBUTION SYSTEMS 

Trunk main system. Trunk mains are used for Cases I, II r 
and V, except where cone fan is used. Where continuous ven- 
tilation is not necessary or where air change is much greater than 
necessary for proper ventilation, this system is used for Cases 
III and IV, except for cone fans. 

The following instructions are to be observed in laying out the 
duct systems: 

Main duct at fan is to be made the same size as fan outlet, 
which has been given heretofore. Refer to the equalization table 



52 



MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 



given hereafter and note how many pipes 1-inch x 1-inch are 
given as being equal in carrying capacity to this main duct. Di- 
vide this number of 1-inch x 1-inch pipes by the capacity of the 
fan in cubic feet per minute. This will give a fraction which is 
the portion of a 1-inch x 1-inch pipe to be allowed for each cubic 
foot of air. Now multiply the amount of air delivered to the 
base of each flue by the distance of said flue from the fan (dis- 
tance means the length of duct, adding equivalent for turns, etc.), 
and divide this product by the amount of air handled by the 
fan. This will give the "average distance" of all outlets from 
the fan. Next multiply the amount of air to each flue by the 
fraction above obtained in dividing the total cubic feet per min- 
ute by the number of 1-inch x 1-inch pipes in the main duct at 
fan. This will give the number of 1-inch x 1-inch pipes to be 
allowed to each flue. This number of pipes is subject to correc- 
tion as follows : For each one foot by which the distance (includ- 
ing equivalent for bends) from fan to base of flue exceeds the 
" average distance" previously obtained, one-third of 1 "per cent 
is to be added to the number of 1-inch x 1-inch pipes previously 
allowed for each flue. If the distance is less than the " average 
distance" the correction is to be deducted instead of added. 

Now refer to equalization table and find the size of square pipe 
equivalent to the corrected number of 1-inch x 1-inch pipes for 
each flue. This is the size of the branch pipe at the base of the 
flue. Add all the branches back to the fan on the equalization 
table, and if the work is correct it will add up the size of main 
duct you started with. 

Take an example : Fan with 54-inch x 54-inch outlet to handle 
28,000 C.F.M. 54-inch x 54-inch pipe = 21,000 1-inch x 1-inch 
pipes, 21,000 ~ 28,000 = 0.75. 



OUTLET NUMBER 


DISTANCE FROM 
FAN IN FEET 


C.F.M. 


C.F.M. TIMES 
DISTANCE 


NUMBER 1 INCH X 
1 INCH PIPES 


1 

2 

3. 

4 


50 

50 

60 

110 


6,000 

2,000 

10,000 

10,000 


300,000 

100,000 

600,000 

1,100,000 


4,500 
1,500 
7,500 
7,500 








2,100,000 





2,100,000 -f- 28,000 = 75 feet (the average distance) 



HEATING AND VENTILATION 



53 



OUTLET NUMBER 


DISTANCE TO BE 
CORRECTED FOR 


AMOUNT OF 
CORRECTION 


CORRECTED NUM- 
BER OF 1 INCH X 
1 INCH PIPES 


SIZE OF BRANCH 


1 


feet 

-25 
-25 
-15 
+35 


-375 
-125 
-375 

+875 


4,125 
1,375 

7,125 

8,375 


inches 

28x28 


2 


18x18 


3 


35 x35 


4 


37x37 







The main to carry branches Nos. 3 and 4 would be 8375 + 7125 
= 15,500 = about 47-inch x 48-inch, etc. 

Rectangular pipes to be same area as square pipe when ratio of 
width and depth is not more than 3 to 1. When this ratio is 
greater, add to area as follows: 10 per cent for a ratio of 4 to 1, 
20 per cent for a ratio of 6 to 1, 30 per cent for a ratio of 10 to 1, 
etc. 

If round pipes are used in some places the diameter of same = 
1.10 times side of square pipe. 

If round pipes are used throughout they can be handled just 
as we handle square pipes, for the equalization table applies to 
round as well as square pipes, but not to both at the same time. 

In starting from the fan it is only necessary to make main pipe 
same area as fan outlet. 

Plenum chamber. Section of plenum chamber to be large 
enough to produce a velocity of not over 250 feet per minute, 
across it, and should be as nearly square as possible. 

Velocity in ducts from chamber to be about 800 feet per minute 
for cone fans and from 900 to 1200 for steel plate and other fans. 

By-passes, etc. By-passes around heating and tempering coils 
to be not less than 10 per cent nor more than 15 per cent of the 
gross area of the coil when they are provided withthermostatically 
controlled dampers. By-passes under heating coils of plenum 
chamber and double-duct systems have no dampers and should 
be not less than 25 per cent of the gross area of the coils. 

Vertical flues and registers. Velocity in vertical flues to regis- 
ters to be about 600 feet per minute, and through registers to be 
200 feet through gross area, which gives about 300 feet over the 
net area. When air is admitted over 10 to 12 feet above the floor 
the speed through registers may be increased to 400 feet per 
minute of net area. Floor registers are never used. 



54 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Resistance of ducts. The following formula, which is accepted 
as good practice, is used: 

IV 2 
P= 25^00? When 

P = loss of pressure in ,ounces per square inch. 
I = length of pipe in feet. 
V = air velocity in feet per second. 
d = diameter of round duct in inches. 
(To reduce ounces to inches of water multiply by 1.73.) 

Should the duct be rectangular the size of equivalent round 
duct is found by the formula: 



D=V— 



32a 3 6 3 



(a+6)' 

when D = diameter of round duct, and a and b = the dimen- 
sions of rectangular duct. The resistance can then be figured as 
for a round duct. 

The following formula is more generally used : 

p _ KSV 2 

A ' 

in which the symbols are the same as used above except : 

S = rubbing surface in square feet. 

A = area of duct (regardless of shape) in square inches. 

K = 0.00012 for galvanized piping. 

K = 0.00022 for brick or concrete ducts. 

V = air velocity in feet per second. 

Bends. Bends in square and rectangular pipe should be turned 
on a true circle; it is entirely practical to make them in this way. 
Branches from mains are made on easy curves as a true warped 
surface from outlet in main duct to point where branch duct as- 
sumes its true section. 

When so constructed the resistance of each elbow is equivalent 
to a certain number of diameters or (in case of rectangular ducts) 
widths, as follows: 



HEATING AND VENTILATION 



55 



Radius of throat to diameter 
or width of pipe 

(square turn) 



2 and above 



Equivalent number of diameters, 
or widths, of straight pipe 

100 
65 
30 
10 

6 

5 



Great care must be taken to insure that air ducts run as directly 
as possible and that changes in relative dimensions, offsets, etc., 
are avoided, as each such change adds a small amount of friction. 

Branches should in general be taken from the side of main and 
the depth of branch at main should be same depth as main and 
be connected to main as nearly tangent to main as possible. 

Example: A 12-inch x 12-inch branch to be taken from a 20- 
inch x 48-inch duct, the branch at main to be 7| inch x 20-inch 
and the taper made to 12-inch x 12-inch before the 90° turn in 
the branch is started or taper made in the bend. 



EQUALIZATION TABLE 



"A" 


"b" 


"A" 


"b" 


"A" 


"b" 


1 


1 


20 


1,788 


39 


9,498 


2 


5 


21 


2,020 


40 


10,119 


3 


15 


22 


2,270 


42 


11,432 


4 


32 


23 


2,537 


44 


12,842 


5 


60 


24 


2,821 


46 


14,351 


6 


88 


25 


3,125 


48 


15,963 


7 


129 


26 


3,446 


50 


17,678 


8 


181 


27 


3,788 


52 


19,499 


9 


243 


28 


4,148 


54 


21,428 


10 


316 


29 


4,528 


56 


23,468 


11 


401 


30 


4,929 


58 


25,620 


12 


498 


31 


5,351 


60 


27,886 


13 


609 


32 


5,793 


62 


30,268 


14 


733 


33 


6,256 


64 


32,768 


15 


871 


34 


6,741 


66 


35,388 


16 


1,024 


35 


7,247 


68 


38,131 


17 


1,191 


36 


7,776 


70 


40,996 


18 


1,374 


37 


8,327 


72 


43,988 


19 


1,573 


38 


8,901 


74 


47,106 



56 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Column "A" is the diameter or side of the square pipe in ques- 
tion. 

Column "b" is the number of 1-inch diameter or 1-inch x 1-inch 
square pipes equivalent to the pipe in question. 

Dampers and deflectors. At each branch a deflector with 
easy and quick adjusting device should be provided. Deflector 
should be large enough to close branch completely. When this 
is not practicable, place a damper in the branch duct. 

In exhaust piping (when exhaust fan is used) place damper in 
each branch duct. 

Example : If a 12-inch diameter pipe will carry a certain amount 
of air a certain distance with a certain loss of pressure, there 
would be required 498 1-inch diameter pipes, or 498 -f- 88 = 5| 
6-inch diameter pipes, to carry the same amount of air the same 
distance with the same loss of pressure, or 498 1-inch x 1-inch 
pipes would have the same carrying capacity as one 12-inch x 
12-inch pipe, etc. 

A more extended table of this kind is given in Trautwine's 
Pocketbook under the heading of " Square Roots of Fifth Powers." 

The formula is : 

N= aII±)\ when 



- #)'■ 



A = diameter if round, or side if square, of larger pipe. 
b = diameter if round, or side if square, of smaller pipe. 
N — number of smaller pipes to equal in carrying capacity 
one large pipe. 

Air washers. Air washers are installed except in very unusual 
cases. In any event the apparatus is arranged and designed 
for the future installation of an air washer. 

Most of the standard makes of washers and eliminators are 
about 8 feet total depth and the cross section is such as to give 
through them about 500 feet per minute velocity, excluding the 
portion cut off by the settling tank. 

A good washer will saturate the air passing through it to 60 
to 70 per cent of the dew-point. It is desirable to carry as much 
moisture in the air of the rooms as possible, to avoid condensing 
same on windows. The maximum percentage of saturation that 



HEATING AND VENTILATION 



57 



can be carried to avoid such trouble appears to be about a mean 
proportional between the inside and outside temperatures. Thus 
with 70° inside and 10° outside this percentage of saturation 
would be (70 + 10) -4- 2 = 40 per cent. 

Frictional resistance. The following data covering a well- 
known air washer are taken as representative of the standard 
makes: 



VELOCITY, FEET PER 
MINUTE 


IN "WASHER PROPER 


IN ELIMINATOR 


TOTAL 


450 


0.10 


0.14 


0.24 


500 


0.12 


0.17 


0.29 


550 


0.13 


0.21 


0.34 


600 


0.14 


0.24 


0.38 


650 


0.19 


0.26 


0.45 



The friction is inches water guage. 

Preferable velocities. A speed of 450 for small washers to 550 
for large ones is used as a standard. 

Pumps. Each washer has a separate centrifugal pump, driven 
by a direct-connected motor used for no other purpose. 

The following table is used as a guide in selecting pumps and 
motors : 



C.F.M. 


SUCTION 


DISCHARGE 


SPEED 


B.H.P. 




inches 


inches 






5,000 


2 


If 


900 


ii 


10,000 


2 1 


2 


900 


if 


15,000-25,000 


3 


' 2-1 


750 


2| 


30,000-50,000 


3 


3 


750 


31 


55,000-70,000 . 


3| 


3^ 


650 


4 


80,000-100,000 


4 


4 


650 


41 



There is considerable variation in the speeds and B.H.P. of 
pumps of the various makes, therefore when laying out the wiring 
the motors are wired for about twice the B.H.P. given. 

Humidifying systems. Humidifying systems are generally 
installed with air washers. These consist of a closed feed water 
heater between the pump and washer, the steam supply to which 



58 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

is regulated by a humidostat, a steam coil in the air washer tank 
or a steam jet in the washer tank. Unless steam at a pressure of 
5 pounds or more is always available one of the two former are 
necessary. 

Different makers of air washers vary somewhat in their methods 
of humidifying and control of same and with this in view the 
office does not go into details as to these points but states the 
conditions to be met and the result that must be secured. 

The results that must be secured are that the air must never 
leave the washer above 70° and the controlling devices must be 
capable of easy adjustment to vary the percentage of relative 
humidity anywhere from 45 per cent to as high as the outside tem- 
perature will permit. 

The manufacturers generally do this. 

Temperature losses. The loss in temperature of the air pass- 
ing through an air washer is capable of rather exact determina- 
tion for a given set of conditions, but conditions are so variable 
that the worst conditions that may be expected are used as the 
basis of calculation. 

It has been found in practice that the loss in temperature is 
8J° F. for each grain of moisture absorbed per cubic foot of air. 
It is the moisture absorbed that is the uncertain part. The fol- 
lowing example will illustrate: Inside temperature 70°. Outside 
air 0°. Outside humidity 50 per cent. Maximum humidity 
that can be carried is 70 -f- 2 = 35 per cent. At 35 per cent satu- 
ration and 70° each cubic foot of air contains 2.8 grains. We may 
assume that the air will be 80 per cent saturated on leaving the 
washer. Outside air at 50 per cent saturation and 0° contains 
0.25 grain per cubic foot. Now 2.8 —0.25 = 2.55 grains moisture 
absorbed by each cubic foot of air. By figuring the heat required 
to evaporate one grain it will be found that it is just sufficient 
to drop the temperature 7.6°. But there is a further loss due 
to cooling effect of the water, etc., making the total loss 8J° for 
each grain evaporated per cubic foot. 

We had 2.55 grains evaporated and our temperature loss would 
be 2.55 X 8} = 21.6°. Since each cubic foot of air at 80 per cent 
saturation is by our hypothesis to contain 2.8 grains water, the 
amount of water at 100 per cent saturation would be 2.8 -f- 80 
= 3.50 grains. The temperature of air required to maintain a 



HEATING AND VENTILATION 59 

dew-point of 3.5 grains is 45°, which is to be the temperature 
leaving the washer. Our tempering coil must then raise the air 
to 45° + 21.6° = 66. 6°, and our heater coil must raise it from 
45° to whatever temperature we have assumed at the fan. 

In view of the varying outside air conditions it is the practice 
of the office to have sufficient tempering coils (not less than three 
sections deep) to raise air from minimum outside temperature to 
about 67J° and have it under accurate thermostatic control, and 
assume a temperature loss of 17J° in passing through the air 
washer. 

Automatic control of coils when air washers are used is dis- 
cussed under that heading. 

Double inlet fans. It has been found that so long as the area 
of the inlet is smaller than the area of the outlet the capacity of 
the fan varies directly as the cube of the diameter of the inlet. 
A fan with two inlets will handle twice as much air as with one 
inlet of the same diameter, provided the " equivalent" of the two 
inlet areas is not greater than the outlet of the fan. 

If we had a fan the standard inlet to which is, say, 60-inch di- 
ameter, and wanted to put two inlets and have the capacity of the 
fan remain the same, the diameter of each inlet should be 60 -t- 
■\/~2 = 48 inches. In other words, two 48-inch diameter inlets 
are equivalent to one 60-inch diameter inlet. The horsepower 
for the fan would not be materially changed by this change in 
inlets. 

If we should take the fan above, in which the one 60-inch di- 
ameter inlet is about the same area as the fan outlet, as is usually 
the case, and put another inlet of the same size, the capacity of 
the fan would be increased by y/ 2 as a multiple. It would not be 
doubled as above, because the equivalent of the two 60-inch in- 
lets is much larger than the standard outlet. The pressure would 
be doubled, the capacity increased nearly 50 per cent, and, as the 
power varies as the product of pressure and capacity (assuming 
the efficiency to remain the same), the power would be increased 
by three times. 

Shop testing of fans. Shop tests of fans are not now required 
to be made in the presence of a representative of the office except 
when a style of fan is to be used upon which the office has no ac- 
curate data based upon a shop or other satisfactory test under 



60 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

conditions applicable to the case in question. The standard 
method of specifying a fan when such test is required is to state 
the peripheral velocity of wheel, the minimum diameter of wheel, 
the maximum brake horse-power, and the capacity; and, if re- 
quired by structural conditions (such as ducts of a given size to 
which connections are to be made), the size of inlet or outlet, as 
the case may be, together with any other necessary dimension, 
is specified. 

The total friction loss is carefully estimated; and, in testing, the 
outlet is fitted with a straight pipe about 50 feet long of same size 
as fan outlet. A blast gate made of slats not over 2 inches wide 
is placed at the end of the pipe. The fan is then run at the peri- 
pheral velocity specified. The Pitot tube is inserted about 25 feet 
from the fan and the slats in the blast gate are withdrawn until 
the average static pressure at the Pitot tube is equal to that 
specified (allowance being made for friction between fan outlet 
and Pitot tube according to formulae hereinbefore given). When 
these conditions are adjusted, the capacity and power are meas- 
ured. 

Capacity is measured by high-speed anemometer at end of 
pipe just inside the blast gate, and is checked by the Pitot tube. 
Ordinarily, measurements made at the inlet are useless on account 
of the whirl of the air giving unreliable readings, but sometimes 
reliable anemometer readings can be made on the inlet side, as 
in the air intake to cold-air room, etc. 

Power is measured in the most convenient and accurate manner. 
It is generally preferable to have the fan driven by the motor 
that is to run it after installation, measure input to motor and 
correct for motor efficiency and transmission loss. 

The cross section of the duct is divided into a number of rect- 
angles of equal area if rectangular, and if circular it is divided 
into concentric rings of equal area; and readings are taken in the 
center of each subdivision. 

The average static pressure is the average of all the static 
readings and the average dynamic pressure is the average of all 
dynamic readings. 

The average velocity in the duct is the average of all the ve- 
locities. The velocity at any given point can be determined by 
the following formula: 



HEATING AND VENTILATION 61 

F=15.9 J 460+T VeL . n wMch 

jBar (m.) 

F = Air velocity in feet per second. 

T = Temperature Fahrenheit. 

Bar. in. = Barometer inches mercury. 

Vel. in. = Velocity pressure inches water (water at 72°). 

This formula is based air at 50 per cent saturation. 
For air temperature of 62° and barometer of 29.91 inches mer- 
cury the formula becomes 

V = 67.50 VVel. in. 

An easy rule to remember for temperatures about 60° is 1- 
inch water velocity pressure = 4000 feet per minute air velocity. 
For other velocity pressures the air velocity varies directly as the 
square root of the pressure; thus | inch water = 1000 feet per 
minute air velocity and 4 inches water pressure = 8000 feet per 
minute air velocity. 

If the different velocity pressure readings in the different sec- 
tions of the pipe are very close together it will be sufficiently ac- 
curate to compute the average velocity from the average velocity 
pressure, but if there is considerable variation, as there nearly 
always is, the air velocity for each reading should be computed 
and the average velocity arrived at as an average of all velocities. 
From the known area of the section the volume in cubic feet per 
minute can be computed. 

The Air Horse Power (A.H.P.) or work done by the fan can 
be computed from the formula 

A „ p C.F.M.XD.P. . 

A -H.P.= AQ , — m which 

6350 

C.F.M. = cubic feet air per minute. 

D.P. = Dynamic pressure inches water = static pres- 
sure plus velocity pressure. 

This last formula is good for any air temperature and any 
barometer reading with water at 72°. 



62 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

This air horse power divided by the brake horse power gives 
the efficiency of the fan. 

There is always a little static head at the fan inlet. This sta- 
tic head exists to very nearly the same extent whether the fan 
has its resistance on the outlet or the inlet. It is very hard to con- 
vert it into any useful work and in such tests it is charged up against 
the fan, no allowance being made for it. 

A Pitot tube made similar to the one described below has re- 
cently been put through an elaborate calibration test by the 
America Blower Co. of Detroit. Their standard was the Thomp- 
son electric air meter, the accuracy of which has never been ques- 
tioned. These tests proved conclusively that for the practical 
purpose of fan testing such a tube may be considered absolutely 
correct. 

The Pitot tube used by the office has a foot about 8 inches 
long, with an outer tube f-inch diameter and an inner tube yq- 
inch diameter. The inner tube is turned against the current of 
air and at the U tube registers the dynamic pressure. This inner 
tube is continuous. The outer tube has a -^-inch diameter hole 
on each side about 5 inches from the toe to receive static pressure 
and at the heel a ^--inch tube runs to the same U tube as the 
inner tube, and, being connected to the opposite leg, the air ve- 
locity pressure can be read on the U tube. A "Y" may be in- 
serted in the rubber connection and run to another U tube to read 
static pressure. 

The outer tube at the toe is about 2J inches shorter than the 
inner tube, and a bevel (of a piece of cast brass or solder) is made 
for this length and ground until the end of the inner tube comes 
to a sharp edge. 

All tubes are brass and the whole burnished smooth; and they 
must be tested statically for leaks. 

A tube as above described, carefully made, will give reliable 
results. The writer has tested such a tube by revolving it on a 
shaft in still air and found readings exactly as calculated. 

Vacuum systems. Mechanical vacuum systems, i.e., those 
having a vacuum pump attached to the return mains, are installed 
by the office only when exhaust steam is intended to be used for 
heating, or when a district heating service using this kind of sys- 
tem is available. In the latter case it is customary (except iu 



HEATING AND VENTILATION 63 

the largest buildings) to install a 2-pipe system, with a special 
arrangement of the return valves at the radiators, so that it will 
operate as a gravity-return system from boilers installed in the 
building, or as a vacuum system when the outside service is used. 
The steam mains are proportioned for a gravity-return 1-pipe 
system. 

The vacuum valves on the return of the radiators are of the 
automatic type, designed to pass air and water readily, but only 
a minimum amount of steam. 

The pumps for producing the vacuum are the ordinary type of 
vacuum pumps having an automatic control of the vacuum car- 
ried in the return at the pump by controlling the steam supply 
to the pump. Pumps are installed in duplicate, and are invaria- 
bly steam-driven. 

The pumps discharge into an air-separating tank so located 
that the water will flow to the boiler feed-pumps through the 
feed-water heater by gravity. No definite rule can be given as 
to the size of tanks. About 1 cubic foot capacity to 2000 square 
feet of radiation would be conservative', using a tank 18 inches di- 
ameter by 36 inches long as a minimum. A 2-inch vent line 
should be carried to the atmosphere to allow the air to escape. 

The make-up water for the boilers should be fed into the inlet 
of the pump; but there should be a make-up feed connection to 
either the air-separating tank or the feed-water heater, controlled 
by a float valve, to insure water for the feed-pumps in the event 
that the makeup valves at the pump inlets should be neglected. 

The steam and return mains are sloped in direction of flow 
when possible. The base of each riser and the ends of mains are 
dripped into the return through a special valve, same as is used 
on radiator returns; but if the building *is less than seven stories 
high the drips at base of risers may be safely omitted. 

The return mains are usually not covered unless necessary for 
temperature control. 

It is not considered advisable to lift the water of condensation, 
but it can be done successfully if a separate return main is run for 
the low radiators. In the post office at New Orleans, La., the 
return main is at the first-floor ceiling and takes care of radiators 
about 9 feet below, and operates satisfactorily. 

The following sizes of steam and return mains are reliable for 



64 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



vacuum systems. The quantities given are in square feet direct 
radiation per hour, and the distance is from the engine to the 
heater, one way: 











SUPPLY PIPING 








RETURN PIPING 


4> 

0) 


t-i •+* 

O CD 

©.a 

» cq » 

S £ G 

03 ET.^ 

3H o 


O (o 
IB 

y rt cd 
PI S ft 

O (S_ 


Length of Supply Piping in Feet, from Source of Supply- 
to Farthest Radiator. Allowance for Elbows and Valves 
must be added to Measured Distance. Pipe Capacities 
in Square Feet of Direct Cast Iron Radiation given for 
each Length 


CD 
ft 

a aj 

> 


CD 

a 
P4 

"o3 

a 

Is 

K 


■+» 03 

o 


ft 


100 


200 


400 


600 


1000 


1500 


2000 


in. 




















in. 


in. 




3 

4 


2 


2 


65 


50 


40 


35 


30 


25 


20 


i 

2 




20 


1 


2 


3 


120 


100 


80 


70 


60 


50 


45 


1 
2 




45 


U 


2 


3 


240 


190 


150 


130 


110 


90 


80 


1 
2 




80 


14 


3 


5 


390 


310 


250 


210 


180 


150 


136 


3 

4 




136 


2 


5 


7 


870 


670 


540 


460 


390 


330 


290 


3 

4 




290 


2\ 


6 


9 


1,600 


1,250 


1,000 


870 


740 


620 


550 


3 
4 




550 


3 


9 


14 


2,590 


2,040 


1,650 


1,430 


1,210 


1,020 


900 


3 
4 




' 900 


84 


10 


15 


3,900 


3,100 


2,500 


2,190 


1,850 


1,570 


1,390 


1 




1,390 


4 


14 


21 


5,480 


4,390 


3,530 


3,120 


2,630 


2,230 


1,960 


1 


1 1 

x 4 


1,960 


5 


19 


28 


9,720 


7,900 


6,460 


5,680 


4,810 


4,110 


3,630 


li 


•I 1 
x 4 


'2,710 


6 


24 


36 




12,870 


10.680 


9,390 


7,980 


6,720 


5,740 


14 


1 1 
A 3 


3,630 


7 


29 


44 




19,090 


15,930 


14,120 


12,040 


10,290 


9,130 




11 

± 2 


5,740 


8 


35 


53 




26,910 


22,680 


20,180 


17,120 


14,330 


12,720 




2 


9,130 


9 


41 


61 




35,580 


30,170 


26,920 


23,150 


19,790 


17,380 




2 


12,720 


10 


47 


70 




46,710 


40,050 


35,860 


30,890 


26,540 


23,610 




2 


17,380 


12 


59 


88 




73,210 


63,870 


57,660 


49,950 


43,080 


38,400 




24 


23,610 


14 


71 


106 








86,400 


75,430 


65,310 
85,770 


58,290 
71,910 




24 
3 


38,400 


15 








58,290 
























3 


71,910 



























When blast coils are on the system, the equivalent direct radia- 
tion equals the total B.t.u. per hour put into the air, divided by 
250. 

Pumps. Sizes of vacuum pumps for vacuum systems may be 
found as follows: "Factor" equals 100 times the number of water- 
seal motor valves plus the actual square feet of direct radiation. 
In case of indirect radiation, or blast coils, reduce the radiation 
to equivalent direct surface by multiplying the actual square 
feet by the B.t.u. condensation per hour and dividing the pro- 
duct by 250 (the usual condensation of direct radiation in B.t.u. 
per square foot per hour). 

After the "factor" is found refer to the following table and 
choose the pump corresponding to the "Factor." 






HEATING AND VENTILATION 



65 



In the table make the steam, exhaust, and discharge pipes the 
size given. Make the suction the size of the main return and 
bush at the pump to size given. All pumps are single-cylinder 
double-acting. 



SIZE OF PUMP 

STEAM WATER 

STROKE 


STEAM 


EXHAUST 


SUCTION 


DISCHARGE 


FACTOR 


FLOOR 
SPACE 


inches 

4x4x5 


inches 


inches 


inches 


inches 


6,830 

7,270 

8,000 

10,680 

11,350 

12,500 

15,125 

15,390 

17,215 

18,000 

19,390 

28,250 

30,600 

34,410 

36,620 

43,627 

48,957 

57,220 

60,250 

82,397 

90,713 

122,500 

133,000 

161,270 

173,720 

219,870 

233,640 

271,440 


inches 


4x4x6 

4x4x8 
4x5x5 


3 
8 
3 
8 


l 

2 

l 

2 


2* 

2| 


2 
2 


11 x34 
11 x34 


4x5x6 
4 x 5 x 8 
4£ x 5| x 8 
4£ x 6 x 5 


3 

8 
3 

8 
1 
2 


1 
2 
1 
2 
3 
4 


3 
3 
3 


2h 
2| 
2| 


13 x36 
13x38 
13x38 


4fx 6 x 7 












4| x 6 x 8 

5 x 6 xlO 
7 x 7ixl0 

6 x 7JxlO 

7 x 8 xlO 
6 x 8 xl2 
6 x 9 x 10 


1 
2 
3 
4 

1 

3 

4 

1 

3 

4 


3 
4 

1 

ii 

l 

U 

l 


3 
4 
5 
5 
5 
5 


pi 

■"2 

3 

4 
4 
4 
4 


13x38 
18x50 
18x52 
19 x 54 

18x52 
19x54 


8 x 9Jxl2 
8 xlO xl2 
8 x 10 x 14 


1 
1 


u 


6 
6 


5 

5 


20x58 
20x58 


10 xl2 xl2 
10 x 10 x 16 


U 


l* 


6 


5 


20x62 


10 x 14 x 16 












12 x 14 x 20 


U 


2 


10 


8 




12 x 16 x 16 




14 x 16 x 20 


2 
24 


3 


12 

12 


10 
10 




16 x 18 x 20 




16 x 18 x 24 




18 x20 x20 


3 


t>2 


14 


12 





In the foregoing table the steam cylinders of the pumps are pro- 
portioned for about 100 pounds steam pressure. Pressures dif- 
fering materially from this would require proportionally different 
steam cylinders. 

Capacity of the automatic return valves : 



66 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

One-half inch diameter, 80 pounds water per hour = 265 

square feet direct radiation. 
Three-quarter inch diameter, 400 pounds water per hour = 

1330 square feet direct radiation. 
One inch diameter, 800 pounds water per hour = 2660 

square feet direct radiation. 

The office does not adopt the practice of running a separate 
return system to take care of the drips from risers and mains. 

No horizontal branch, either stream or return, is made less 
than f inch. It is especially important to observe this if branch 
is to be buried in floor construction. 

All special attachments necessary for the operation of the 'ap- 
paratus are required to be furnished by the contractor when a 
vacuum system is used by the office. 

The specification for such a system must, of course, be some- 
what general to permit free competition. 

MECHANICAL SYSTEMS OF AIR REMOVAL 

These systems are sometimes installed in the larger buildings 
where automatic temperature control is used, or in buildings 
where outside steam service operating on an atmospheric system 
is to be used. In the latter cases it has been found that the me- 
chanical air-removal systems are usually acceptable to the dis- 
trict service companies. The office does not often use an atmos- 
pheric system. 

The steam and return piping is laid out in exactly the same 
manner and with the same sizes as for a 1-pipe gravity-return 
system, and all connections are made in the usual way. 

The exhausting apparatus for plants less than 2500 square feet 
direct radiation, or its equivalent in indirect, is a water-operated 
vacuum pump. The water pressure should be over 20 pounds 
per square inch to insure satisfactory operation. 

In larger systems where high-pressure steam is made, a steam 
jet is used to induce a partial vacuum in the air lines. Velocity 
of steam at jet should be about 900 feet per second. 

In systems above 2500 square feet where no high-pressure steam 
is made a small vacuum pump driven by an electric motor is 
used. 



HEATING AND VENTILATION 67 

The motor has an automatic regulating device, and if water 
or steam is used there should be an automatic control valve so 
arranged as to carry constant vacuum on the air lines. 

The discharge line from the ejector or pump is discharged 
over a cesspool or some such receptacle. 

Care must be taken in the grading of the air lines to insure that 
no pockets are sealed with condensed vapor. Each rising air 
line should have a gate valve. 

In this class of systems, and also in the larger installations of 
the mechanical vacuum type, it is the practice of the office to di- 
vide the radiation into groups and to bring the air lines and va- 
cuum return lines back separately, valving each at the pump or 
ejector. Proper adjustment of these valves will overcome the 
''robbing" of one group by another. The steam mains to the 
respective groups should be valved to correspond, if possible, but 
these valves need not be centrally located as in case of the valves 
on returns. 

The amount of steam used by the ejector varies widely, some 
authorities reporting as little as one-tenth of 1 per cent, and others 
as much as 5 per cent of the total amount of steam condensed. 

The following is a sample specification (all material and labor 
included) for attaching an air-removal system to a system of di- 
rect radiation where the radiation exceeds 2500 square feet and no 
high-pressure steam is available. 

SPECIFICATION 

Air-removal system. Furnish and install an automatic me- 
chanical air-removal system in connection with the heating sys- 
tem of the building. 

For this purpose an electric-driven air exhauster is to be fur- 
nished and installed in suitable manner on concrete foundation 
with cast-iron bedplate. The motor is to be direct connected 
to air exhauster or to drive same by means of silent chain or spur 
gear running in oil bath, or by suitable leather belt. Motor to 
be of proper size and speed and wound for — volts, — current. 
Motor must conform to specification for motors in general in 
another part of this specification. 

There must be an automatic governor designed to start and 
stop motor to maintain a constant predetermined vacuum on air 



68 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

lines. A storage tank and separator which will automatically 
discharge any condensation to waste pipe must be provided on air 
line near pump. The air exhauster must have a capacity suf- 
ficient to keep the entire system free from air and to maintain 
any desired vacuum in the system between 6 and 12 inches. 

Output of motor at full load must not be more than — 
brake horsepower. 

Air valves, air lines, etc. All direct radiators, the ends of all 
steam mains , and the return from coil in hot-water tank are to 
be fitted with approved automatic type air valves of the highest 
grade specially designed for air-exhausting systems. Air valves to 
be nickel plated, provided with union couplings, and not less than 
J-inch pipe connection. To have all metal thermostatic ele- 
ments, no carbon post valve is acceptable. 

Piping in connection with air-removal system is not indicated on 
drawings. Contractor must run same as direct as possible and 
follow runs of steam mains in basement. Horizontal runs from 
air valves to be run in floor construction to risers or at ceiling 
below to mains, same as steam piping. Pipe sizes to be not less 
than the following: Vertical connection to air valves J-mch di- 
ameter; horizontal branches from air valves to risers or mains | 
inch ; risers \ inch and mains in basement 1 inch diameter unless 
otherwise shown on drawing. 

All pipes to be galvanized wrought iron or galvanized mild 
steel and all fittings to be galvanized cast iron. Ends of all pip- 
ing to be reamed after cutting. All joints to be made up with 
asphalt um. 

Gate valves to conform with valves on steam piping to be 
placed on mains and riser connections in basement. The dis- 
charge from exhauster is to terminate over cesspool located near 
exhauster. Hangers, tubes, floor, and ceiling plates to be as 
specified for steam pipes. 

Air lines are not to be covered. Exposed air piping above base- 
ment is to be painted as specified for steam piping. Air piping 
in basement is to be painted same as other galvanized pipe. 

Test of air lines. All air piping run in chases, furred spaces, 
or floor construction must be tested in the presence of the super- 
intendent to a hydrostatic pressure of 80 pounds to the square 
inch and proved tight under this pressure before same is concealed. 



HEATING AND VENTILATION 69 

On completion of the heating system the entire air-removal sys- 
tem is to be tested to a vacuum of 7 inches. This vacuum must 
be obtained by the pump, the pump is then to be stopped, and 
the vacuum must be maintained for one hour without showing 
a decrease of more than 2 inches. During test of air lines all 
communication between air lines and steam piping must be 
closed, but hand valves at pump must remain open. 

Painting. Exhauster, motor, tank, etc., to be filled and rubbed 
at factory and after erection painted two coats lead and oil paint 
tinted as directed by superintendent. 

ESTIMATING DATA FOR HEATING AND VENTILATING APPARATUS IN NEW 

FEDERAL BUILDINGS 

Cost of boiler. Take off 50 per cent from price list Kewanee Boiler Com- 
pany's "Fire box." 

Labor to install and test steel boiler ':• $50 .00 

Foundations, brickwork for boiler and pit in place, per M 20.00 
Foundations, concrete for boiler and pit, per cubic yard. . 8.00 

Stone coping for boiler pit per cubic foot, in place 4.00 

Breeching and stack in place, per pound 0.08 

or per foot, 4.00 

Cast-iron base plate for stack, per pound 0.03 

Direct steam radiators (all heights) set in place, but not 

connected per square foot . 20 

Painting and enameling, per square foot of radiator 0.03 

Highest grade radiator valves and air valves (steam), 

per radiator 3 . 50 

Highest grade radiator valves and air valves (water) per 
radiator (two regular steam type radiator valves are used 

on each hot water radiator) 4 .50 

Air valves at ends of steam mains in place, each 12.00 

Labor on one-pipe steam jobs, per radiator exclusive of 

boiler and breeching 6 . 50 

Labor on two-pipe hot water jobs, per radiator exclusive 

of boiler and breeching 8.00 

Freight and drayage, 3 per cent total cost of boiler, radia- 
tors, pipe, and fittings. 
Superintendence, 1 per cent cost of labor and material. 
Nonconducting covering for pipes and fittings, per square 
foot of radiation (this also includes the boiler and breech- 
ing covering) . 10 

Pipe and fittings, one-pipe steam, per radiator 7.00 

Pipe and fittings, two-pipe hot water, per radiator 10.00 



70 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



Return pipe trench and cover complete in place, per lineal 

foot $1 .50 

Blow-off pot with pipe and valves in place 35.00 

Forty-gallon expansion tank in place with pipe 25.00 

Thermometers in place, each 1 .00 

Sylphon damper regulator in place (water) 20.00 

Board and lodging for men, per day 3.00 

Railroad fare for Federal jobs, average conditions 50.00 

Profit, 20 per cent. 
Cast iron blowoff pots in place exclusive of blowoff valve, sewer 
connection, and vapor vent pipe. 

Size Price Size Price 

18x24 $20.00 30x42 $51.00 

18x30 23.00 30x48 57.00 

18x36 * 26.00 36x36 53.00 

24x30 31.00 36x42 59.00 

24x36 37.00 36x48 65.00 

24x42 41.00 42x42 67.00 

30x30 39.00 42x48 73.00 

30x36 45.00 42x54 79.00 



The following table gives cost in place of pipe, fittings, etc., 
for low pressure heating work. Cost of threads is included in 
cost of pipe in place. Cost of floor and wall sleeves and hangers 
includes cost of cutting in ordinary fire proof construction. All 
pipe and fittings are black and screwed unless otherwise stated 
and are standard weight for 125 pounds pressure. Prices for 
flanged work includes bolts and rubber gaskets suitable for low 
pressure. Radiator valves are the highest grade nickel plated 
rough bodies and finished trimmings. 



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71 



72 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



High grade automatic air valves in place $1.00 

Check, safety and blow off valves in place. 









ASBESTOS PACKED 


SIZE 


SWING CHECK VALVE 


LEVER SAFETY VALVE 


blowofp cocks 
(ikon) 


1 
2 


0.85 


1.25 


1.25 


3 

4 


1.05 


1.45 


1.55 


1 


1.55 


1.75 


1.85 


u 


2.05 


2.60 


2.55 


1* 


2.90 


3.30 


3.50 


2 


4.20 


4.50 


7.00 


2| 


5.05 


4.75 


8.45 


3 


6.85 


6.35 


12.60 


31 


8.20 


8.40 


18.75 


4 


9.85 


10.50 


21.00 



For handling fans and heating coils and placing on foun- 
dation, allow for labor, per ton $12.00 

Standard galvanized-iron air washer complete in place, 
exclusive of freight and foundation. 

Capacity per minute, cubic feet. 

15,000 $900.00 

20,000 1050.00 

25,000 1250 .00 

30,000 1500.00 

40,000 2000.00 

Air washer complete, including air-washer pump and 
motor complete, f.o.b. factory, per 1,000 cubic feet of 

air capacity specified $45.00 

Erection (average) 100 .00 

Freight and drayage (average) 100.00 

Brickwork in cement, per M in place 20.00 

Trench plates in place, fitted and painted, per pound... 0.05 

High-pressure all-steel water-tube boilers, Government 
specification, and tested complete in place and set, but 
no pipe work or breeching, per H.P 20.00 

Feed water heaters in place on foundation, no pipe work, 
per H.P 1 .50 

Boiler feed pump, 6-inch x 4-inch x 6-inch, with drip pan, 
brass fitted, in place on foundation, no pipe work 150.00 

Nonconducting covering in place, with solid brass bands 
and painted two coats fireproof paint, take 50 per 
cent off the 85 per cent magnesia list. This will aver- 
age per square feet radiation . 10 



HEATING AND VENTILATION 73 

Covering on boiler and breeching, per square foot, in 
place $0.20 

One hundred pound pressure, standard design, horizontal 
return-tubular boilers, with all castings, will average 
f.o.b. factory the following prices: 

Boiler _ Pit, setting and founda- 

Inches feet Price tion in place 

42 x 12, without down draft furnace . $300 . 00 $300 . 00 
48 x 12, without down draft furnace . 350 . 00 350 . 00 

48 x 14, without down draft furnace . 400 . 00 400 . 00 

54 x 16, without down draft furnace. 475 .00 450 . 00 

60 x 16, without down draft furnace . 600 . 00 500 . 00 

72 x 18, without down draft furnace . 850 . 00 650 . 00 

To get freight, take square feet of radiation at 10 pounds 
which will cover weight of radiation, pipe, fittings, etc. 
When estimating on freight call 5,000 square feet of 
direct radiation a car-load, and 36,000 pounds of pipe 
a car-load. 

Take freight on Government job at 10.20 per 100 pounds 
and drayage at $3.00 per ton. 

Galvanized ducts, etc., in place, per pound 0.12 

Registers, take 60 per cent off Tuttle and Bailey's list. 

Special valves on return ends of radiators, the receiving 
tank, the automatic vacuum and relief valves on re- 
ceiving tank of atmospheric systems such as the " Dun- 
ham," per radiator 10.00 

This figure is about correct for the Webster Modulation 
system and the Thermograde system, and should also 
. cover the cost of all so-called "Vapor" systems. 

For placing registers, each, add 1 .00 

Labor erecting ordinary indirect stack, each 5.00 

Cast-iron pin indirect, delivered in basement, per square 
foot 0.20 

Blast coils, per lineal foot in place on foundations, exclu- 
sive of freight 0.12 

(To get weight multiply lineal foot by 3.) 

Engine and fan foundations in place, including excava- 
tion, per cubic yard 8 . 00 

Full housed steel-plated fans in place on foundation, 
exclusive of motors and belts : 

3 feet inch diameter wheel 130.00 

4 feet inch diameter wheel 185 .00 

5 feet inch diameter wheel 250.00 

6 feet inch diameter wheel 325 .00 



74 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

7 feet inch diameter wheel $430.00 

8 feet inch diameter wheel 565 .00 

9 feet inch diameter wheel 710 .00 

10 feet inch diameter wheel 930.00 

In estimating the cost of vacuum systems it will be safe to as- 
sume for the average Federal building that each vacuum pump 
on its foundation, complete with governor and suction strainer, 
will cost $350, as the size will average 10 inches x 12 inches 
x 12 inches. Take the special valves on return end of radiators 
and at drip points in piping at $6 each in place. This allows for 
valve and return piping, 

For air line systems allow $5 per radiator for air valve and 
air piping. Electric air exhauster, including separator and auto- 
matic vacuum governor, $400 in place. 

Water-operated exhausters cost $150 each. 

In estimating cost of first-class automatic temperature-control 
systems, allow $15 for each thermostat, $20 for each damper con- 
trolled, and $10 for each steam or water valve controlled. Allow 
$250 for an electric driven compressor and $75 for a water oper- 
ated compressor. For humidity control exclusive of water heater 
allow $200. 

A hydraulic pump will handle fifty thermostats if necessary, 
but in the larger jobs an electrically-operated air compressor is 
used. 

A hydraulic air exhauster is used on "Paul" systems with 2000 
square feet direct surface; above that, electrical or steam exhaust- 
ers are used. 

Especial attention is called to the fact that the foregoing figures 
are correct for certain special conditions in new Federal buildings, 
but are not applicable under all conditions. Used with judg- 
ment, they give accurate results. 



CHAPTER II 

COMMERCIAL PRACTICE IN REGARD TO HEATING FACTORY 

AND OTHER BUILDINGS 

While the following two chapters are not strictly applicable 
to Federal buildings, they are incorporated herein as containing 
much valuable information of general interest. 

The papers were written by heating and ventilating engineers 
in the office of the Supervising Architect, the first by Mr. H. C. 
Russell and the second by Mr. Leon A. Warren, who are specially 
qualified to treat of their respective subjects, the former by reason 
of several years' employment with one of the leading fan manu- 
facturers, and the latter through his connection with a firm 
specializing in the forced hot-water system of heating. 

FACTORY HEATING 

[Note : Most of the calculations in this paper were made on a 
slide rule, which accounts for insignificant arithmetical errors. 
References will frequently be made to the section of this book 
which treats of the heating and ventilation of Federal buildings, 
and to curves and tables which will be found in the back of the 
book.] 

Systems in use. Practically there are only two systems for 
heating factory buildings, i.e., the fan system, and direct steam 
or hot water, each having its various modifications. 

The fan system as a general rule has the following advantages : 
Great flexibility, in that air can be cut off from unexposed por- 
tions of a building and a large part of it forced to the more exposed 
portions : absence of leak pipes overhead ; less liability of freezing 
affords positive ventilation; the humidity of the air inside the 
building can be controlled; and lower steam pressure is required 
to maintain circulation, which is an important consideration if 
exhaust steam is used for heating without a vacuum system. 

Direct radiation has certain advantages in places where a fan 
might stir up dust to settle upon freshly painted or varnished 
surfaces. 

75 



76 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

FAN SYSTEM 

Apparatus. The apparatus usually consists of a fan to circu- 
late the air, a prime mover to drive the fan, a heater to heat the 
air, and a set of distributing ducts to carry the hot air to the de- 
sired points. Air washers are seldom used except where food 
products are handled, or where there are special considerations, 
such as humidity control, etc. 

Fans. Centrifugal fans are usually employed, although the 
disc fan is used in small buildings where the ducts are very short. 

The ordinary type of centrifugal fan is known as the " steel 
plate" fan. It usually has 8 blades. The capacity of fan is 
expressed in cubic feet of air per minute handled by the fan. The 
conditions under which a fan works must be known, because they 
have a preponderating influence upon its performance. Tests by 
the writer, coupled with data from various sources indicate the 
formula given below when proportions of fans are as hereinbefore 
stated for 8-blade fans. 

Capacity. 

C.F.M. = 0.44 DW, as a formula for ordinary factory heating. 
C.F.M. = cubic feet air handled per minute by the fan. 
D = diameter of wheel in feet. 
N = revolutions of wheel per minute. 

Power required. 

D 5 N 3 S 
B.H.P. = .,_ r __ _^_ , for average factory heating. 
12,500,000' & j & 

Symbols same as before, except S, which equals 1.00 for air 

handled at 0°, and for any other temperature as t — 



v 



460 



460 + £ 

If T should be below 0° it would of course be considered negative. 

The B.H.P. is the power actually applied to the fan shaft. 

The above formula for power is for a wheel about 6-foot diame- 
ter. For smaller wheels add 5 per cent for each one foot differ- 
ence in diameter. 

Sirocco fans. The proportions of these fans have been pre- 
viously stated. The capacity and power for ordinary factory 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 77 

heating are as follows, the symbols being the same as used here- 
tofore : 

C.F.M. = 1.10DW. 

D*N*S 



B.H.P. = 



2,250,000 



A test of an 8-foot multiblade fan showed that the fan deliv- 
ered 75,600 C.F.M. at 149 R.P.M. against a static pressure on the 
outlet of 1.11 inches of water (inlet free), with a B.H.P. equal to 
33.9, at 74° temperature and barometer at 29.76. In this case 
the outlet was 64 inches x 64 inches instead of the standard size 
used by the manufacturer. 

The above formulae for capacity and power given for heating 
work are based on having a set of discharge ducts which shall equal- 
ize to the standard fan outlet (not blast areas, which is usually 
about 40 per cent of the area of fan outlet), as explained here- 
after. Or, to put it in another form, the formulae are correct when 
the pressure due to the velocity of air at the fan outlet is about 
40 per cent of the total friction losses in the heater and ducts. 

Double-inlet fans. Double-inlet fans are not often used in 
factory work, as single-inlet fans usually make a more compact 
outfit. 

Cone fans. These fans have a large field of usefulness in heat- 
ing and ventilating work where the power must be reduced to a 
minimum. They require large ducts and much floor space and 
are seldom used in factories. 

The reason for the low power consumption is that in the case of 
a steel plate fan the air is taken from the periphery of the wheel 
by means of a scroll, the outlet of which must be relatively small 
to prevent a so-called " back-lash" of air, resulting in a high 
velocity of air through this outlet. If large ducts are used this 
velocity will be reduced and a great part of the pressure in the 
fan, required to produce this high velocity in the beginning, will 
be lost. In the case of the cone fan this high velocity is never 
produced, as the inlet, which represents the highest velocity, is 
usually about 50 per cent greater in area than the inlet or outlet 
of a steel plate fan which would be selected to do the same work. 

However, a steel plate fan of which the standard outlet equals 
the area of the discharge ducts will handle the air with less power 



78 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS ' 

than a cone fan, because its true mechanical efficiency is higher 
than that of a cone fan. 

The following formulae apply to cone fans : 

C.F.M. = 48DW. 
D 5 N*S 



B.H.P. = 



14,000,000 



Care should be exercised in every detail of cone fan installations. 
The combined area of the air ducts should not be less than the dis- 
charge area of the wheel, i.e., the circumference times width of 
periphery, and the free area of the heater should be about the 
same as the area of air ducts. 

The following facts have been determined both theoretically 
and practically for all kinds of centrifugal fans : 

The C.F.M. varies directly as the speed; the pressure varies 
directly as the square of the speed; and the brake horse-power 
varies directly as the cube of the speed. 

The above are true, of course, only so long as conditions of 
the inlet and outlet resistance are maintained the same. 

The indicated horse-power of the prime mover may vary about 
as the square of the speed, depending upon the kind of prime 
mover used; but this discrepancy is due to a change in the 
efficiency of the prime mover at different loads. The power actu- 
ally applied at the fan shaft will vary exactly as the cube of the 
speed. 

At the same speed as the resistance is inserted in the inlet or 
outlet, as by the closing of a damper, the capacity and power will 
decrease and the pressure will increase. 

The " blast area" of a fan is the area of discharge opening over 
which the fan will maintain a dynamic pressure equal to the pres- 
sure corresponding to the peripheral velocity of the fan tips. 
When this area is increased the pressure will decrease, and vice 
versa. Many authorities state that the pressure does not in- 
crease on reduction of the area of discharge below blast area, but 
the writer has always found that it does with 8-blade fans. 

The blast area need not be considered in ordinary heating or 
ventilating work, as the restriction should never be great enough 
to cut the effective area of discharge down to blast area, which is 
about 40 per cent of the area of fan outlet, as previously stated. 



COMMEECIAL PRACTICE IN REGARD TO HEATING BUILDINGS 79 

DISC FANS 

In this type of fan much depends upon the number of blades, 
their angle, whether straight or curved, etc. Disc fan outfits are 
uniformly constructed as "blow through" type. In small build- 
ings these fans will give satisfaction for heating, but a large mar- 
gin of safety must be allowed, as their operation is materially 
affected by many apparently trifling things. For fans with about 
twelve blades the following formulae may be used : 

C.F.M. = ADW. 

D 5 N 3 S 



B.H.P. = 



C ' 



All symbols are the same as previously given except A and C, 
which are as follows : 

Case I. Free inlet and delivery, as a fan set in a window to 
supply air or to exhaust from a large room. 

Case II. Delivering or exhausting air through not more than 
the equivalent of 100 feet of straight pipe the diameter of the 
fan. 

Case III. Delivering air through same amount of piping and 
a heater not more than 20 pipes deep and with velocity through 
heater not over 1000 feet per minute. 

STRAIGHT-BLADE DISC FAN 

"A" "C" 

Case 1 0.70 42,500,000,000 

Case II 0.60 33,000,000,000 

Case III 0.50 27,000,000,000 

PROPELLER TYPE 

"A" "C" 

Case 1 0.85 46,000,000,000 

Case II 0.65 40,000,000,000 

In Case II the peripheral velocity of wheel should be not less 
than 5000 feet per minute, and in Case III not less than 7500 feet. 

The free area of the heater should not be less than the area of 
the fan, and the main air duct about equal to free area of the 
heater. 



80 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

With the same fan and the same conditions as to inlet and out- 
let, the capacity, pressure, and power vary in the same manner 
as given for steel plate fans of the centrifugal type; but when a 
disc fan is running at a set speed and the inlet or outlet is re- 
stricted (as by the closing of a damper) the power will increase, 
which is just the reverse of what happened with a steel plate 
fan. The increase is so rapid that it is perfectly possible for the 
fan to take three times as much power with the damper fully 
closed as it would with the damper fully open. An engine on 
this increased load would slow down without damage, but a motor 
not protected by some kind of overload-release would be burned 
up in short order. This feature therefore requires care, especially 
in connection with motor-driven fans. In the case of some of 
the curved- blade disc or propeller fans the increase of power 
with the insertion of resistance would not be so noticeable, as 
such fans have to some extent the properties of centrifugal fans. 

HEATING COILS 

Heaters used for steam are usually the cast-iron sectional-base 
type, with heating surface composed of 1-inch wrought-iron pipe, 
or the all cast-iron heaters such as the "Vento" made by the 
American Radiator Company. 

In some makes of the sectional-base type the base is divided 
into two compartments by a horizontal partition, one compart- 
ment being for steam and the other for condensation. This par- 
tition may be solid, or water seal inside the base may connect 
the two chambers. In the former case, which is the preferable 
arrangement, a third connection called the bleeder is necessary to 
take care of the water of condensation which drains back into 
the steam compartment. 

If pipe coils are to be used mitre type coils are always preferable 
on account of the less liability of air binding. 

In some cases a plain box base is used which has no interior 
partitions of any kind. 

The data given in a preceding chapter on heating and ventila- 
tion, give all data required as to temperature rise, condensation, 
friction, etc. 

For factory work the velocity through the heater is usually 
about 1200 feet per minute, and the heater 20 to 24 pipes deep. 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 81 

Tappings. For exhaust or low-pressure steam with gravity 
returns the tapping of the base should be as follows : 



POUNDS STEAM PER HOUR PER SECTION 


STEAM TAP 


DRIP TAP 


BLEEDER TAP 


80 


inches 

2 

2| 

3 

3| 

4 


inches 

u 

H 

2 

2h 


inches 

3. 


160 


3 


320 

480 




950 


H 



The standard "Vento" tapping is 2| inches for steam and re- 
turn, but 3 inches or 3J inches tappings for the feed sections may 
be obtained on special order. 

The "Vento" has, of course, no bleeder connection. The drip 
connection should be one-half the diameter of steam connection 
plus 1-pipe size. 

The writer has seen successful installations in which the quan- 
tities of steam supplied by tappings were almost double those 
given above. If the mains are short and the water line is 3 feet 
or more below the coils the quantities may be increased 25 per 
cent; and another 25 per cent may be added if the coil are "Vento" 
or "top feed." 

Steam and return piping. The steam pipe is usually carried 
overhead from a convenient point on the exhaust line or from the 
boiler. The return is usually carried in a pipe trench discharg- 
ing into a pot trap, a hot well, a feed pump and receiver, or a 
return trap. Sometimes it is wastefully trapped into the sewer. 

For gravity work the writer uses D'Arcy's formula, which when 
simplified for steam entering at 5 pounds pressure is 



D 



"ILW 2 

~Skp 



when 



D 
L 

W 
P 

K 



diameter of pipe in inches. 

length of pipe in feet. 

pounds steam per minute. 

loss of pressure allowed, usually taken as 1 pound 

per 300 feet of steam travel. 
a constant varying with the size of pipe as follows : 



82 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Diameter (inches) 1 2 3 4 5 6 7 8 

K equals 104 140 160 169 173 170 183 187 

For steam above 30 pounds pressure, make steam main one- 
half of the diameter given above; between 15 pounds and 30 
pounds make diameter two-thirds that given by the formula; 
below 15 pounds same as given by formula. 

Return main one-half diameter of steam main plus 1 pipe size 
and make it "wet." As a rough rule the bottom of the coil 
should never be less than 2 feet above the water line in receiver, 
pump governor, trap, or whatever is used. 

High and low pressure steam. Most authorities agree that 
pressure on coils should not be over 5 pounds for best circulation. 
Arrangements should always be made to use live steam through 
a pressure-reducing valve to supply the heaters when the main 
engines which normally supply the exhaust steam are not running. 

PRIME MOVERS 

Engines are quite generally used in factory work. They are 
usually direct-connected to the fan without fly wheel or governor, 
as the fan wheel is a good fly wheel and prevents the engine from 
speeding because the power required increases so rapidly as the 
speed increases. 

Vertical engines are generally used except the very largest fans. 
On the direct-connected or fixed-eccentric engines, most makers 
set the cut-off at 50 per cent, but in figuring for sizes the cut-off 
should be taken as about 5-16. 

If exhaust or low-pressure steam is used in the coils the fan 
engine exhaust should be connected through an oil separator into 
the low-pressure main. If steam at high pressure is used in the 
coils the fan-engine exhaust is usually connected through an oil 
separator into a separate section of the heater-coil, usually the 
outside section. This section would of course have to have sepa- 
rate return trap, etc., from the sections on high pressure. 

No engine exhaust should be connected to a heating system with- 
out a back pressure valve at a convenient point on the exhaust 
line to regulate the back pressure carried on the engine. 

If motors are used they should be direct-connected to the fan 
when the speed is high enough to warrant it. 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 83 

Flange couplings are quite generally used for both engines and 
motors, although some forms of flexible coupling is often used, 
and sometimes where heavy loads are to be carried the fan and 
prime mover shaft is in one piece. 

Belts. Belts should have the " pulling" side on the bottom if 
possible. The horse-power transmitted per inch of width by a 
leather belt J inch thick at various speeds is as follows : 

Velocity in feet 
per second Horse-power 

10.. .' 0.84 

20 ■. 1.75 

30 2.58 

40 3.32 

50 3.98 

60 4.51 

70 • 4.91 

80 5.15 

90 5.20 

For other commercial thicknesses of belt the horse-power trans- 
mitted varies directly as the thickness, but the maximum velocity 
for any belt for good operation may be considered as 90 feet per 
second. 

Pulley centers should be preferably 10 or 20 feet apart, depend- 
ing upon relative sizes of pulley. Long slow-moving belts give 
best service. Centers less than 8 feet apart will seldom be satis- 
factory. 

Chain-drives. For short centers and considerable reductions 
in speed some of the patented chain-drives give good results, al- 
though they are not always entirely noiseless. 

Sprockets should generally not be more than 4 feet apart. 

Gears, etc. Occasionally back-geared motors are resorted to, 
but gears should be avoided where possible. 

Humidifiers. In textile mills and certain other kinds of fac- 
tories the humidity of the air must be under absolute control. 
This can best be accomplished by an air washer and humidifier. 

In one well-known system the air is first drawn through a spray- 
type air washer and eliminator. The water supplied to the washer 
is heated, the temperature of this heated water being controlled 
automatically by a special controlling apparatus. 



84 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

The conditioning of air for textile mills as regards its relative 
humidity has been reduced to a science. When such problems are 
encountered it is best to obtain the advice of some of the reliable 
firms which manufacture such apparatus and guarantee results. 

Spinners have found that the cost of installation and operation 
of the best humidifying apparatus is small compared with the 
consequent profits in better yarns and the reduced loss in manu- 
facture. 

In factories where the humidity control need not be so exact, 
some of the simpler and cheaper devices may answer the pur- 
pose. 

When designing fans, etc., for this kind of work it is important 
to remember that the weight of air per cubic foot decreases very 
markedly as the point of saturation is approached. Any engi- 
neer's handbook will give the necessary information. 

Ducts and flues. Ducts and flues are usually made of galvan- 
ized iron of the following gages : 

ROUND DUCTS 

To 15 inches dia. No. 26 U.S.S. gauge 
16 inches to 30 inches dia. No. 24 U.S.S. gauge 
31 inches to 42 inches dia. No. 22 U.S.S. gauge 
43 inches to 54 inches dia. No. 20 U.S.S. gauge 
55 inches to 72 inches dia. No. 18 U.S.S. gauge 

73 inches and up No. 16 U.S.S. gauge 

RECTANGULAR DUCTS 

Up to 18 inches wide No. 26 U.S.S. gauge 

19 inches to 26 inches wide No. 24 U.S.S. gauge 

27 inches to 40 inches wide No. 22 U.S.S. gauge 

41 inches to 72 inches wide No. 20 U.S.S. gauge 

73 inches to 84 inches wide No. 18 U.S.S. gauge 

85 inches and up No. 16 U.S.S. gauge 

By "wide" is meant the longest dimension 

No. 26 U.S.S. gauge weighs 0.91 pounds per square foot 

No. 24 U.S.S. gauge weighs 1.16 pounds per square foot 

No. 22 U.S.S. gauge weighs 1.41 pounds per square foot 

No. 20 U.S.S. gauge weighs 1.66 pounds per square foot 

No. 18 U.S.S. gauge weighs 2.16 pounds per square foot 

No. 16 U.S.S. gauge weighs 2.66 pounds per square foot 

In estimating weight allow 15 per cent for allowable over- 
weight, laps, and waste in the making, according to the simplicity 
of the work. 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 85 

Underground ducts when used are usually made of brick, built 
rectangular in shape, with arched top, and plastered smooth on 
the inside. Terra cotta sewer pipe is sometimes used. 

Vertical flues are usually made of galvanized iron, but in textile 
mills and the like they are usually built in the walls and plastered 
inside. Flues when built in outside walls should be, if possible, 
lined with fire-clay flue lining, which has some insulating qualities. 

Air outlets. When overhead ducts of galvanized iron are used 
an outlet is usually a branch taken from the main pipe and turned 
at such an angle as to discharge toward the wall at a point about 8 
feet above the floor. Each outlet should be equipped with an 
adjustable spring damper controlled by a pair of jack-chains 
reaching to about 7 feet above the floor. 

When brick or tile vertical flues are used and so spaced (as is 
usually the case) as to require no branch piping, a screen or mill 
damper is used. 

Systems of distribution. This is the most difficult part of the 
work, where experience is at a premium and a knowledge of what 
has failed is worth even more than a knowledge of what has been 
successful. It is specially important to refrain from trying to 
make the air perform any unusual " stunts." 

Make it a general rule not to get over 30 feet from an exposed 
wall and not over 20 feet above the floor. This would apply to 
a one-story factory building with no ceiling, and say, a saw-tooth 
roof construction. Such a building up to 60 or 70 feet wide could 
be heated with one line of piping in the center. From this up to 
about 150 feet wide the heating could probably be done with 
two lines. 

Under a smooth ceiling air blown from an outlet toward an ex- 
posed wall, even with a low velocity, will heat evenly from 50 to 
150 feet away, depending on conditions, chief among which is the 
location of the foul-air outlet, which should be at the floor line on 
the same side of the room as the hot-air inlet. 

Usually the foul-air or vent ducts are omitted in factories, but 
many such buildings are tightly constructed and the heating will 
be more uniform if foul-air ducts are used. When air is to be re- 
circulated a system of openings for the return of air to the fan 
should be provided if necessary. Such openings should be ar- 
ranged to give a circulation of air in the rooms. 



86 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Care should be taken in regard to allowing for stair wells, ele- 
vators, etc., that might short circuit the air back to the fan. 

It often happens that apparatus must be on a platform some 
distance above the floor. In such cases when the air is to be re- 
circulated the discharge branches must be led down columns, etc., 
to about three feet above the floor, or a return circulating duct 
must be dropped from the inlet of the heater to about three or 
four feet above the floor; this duct to equal in area the free air 
space in the heater. One or the other or both of these things 
must be done, otherwise the air will circulate around the top of 
the building and never reach the breathing line. If both are done 
it may be possible to keep the breathing line warmer than the 
roof trusses. 

Cone connections. The fan inlet is usually connected to the 
heater casing by a "cone;" a "collar" should never be used. 
Plenty of room must be allowed between the fan inlet and the 
heater, and as a rule no part of the connection must be allowed 
to form an angle of less than 60 degrees with the side of the fan. 
If this is not observed a considerable portion of the heater may 
be "dead." 

Heat losses. The following heat losses have been extensively 
used with good results. They will be found somewhat higher 
than those applicable to Federal buildings on account of the uni- 
formly inferior construction of factory buildings. 

The losses given are B.t.u. per square foot per hour per de- 
gree of difference in temperature inside and outside. 

VARIOUS WALL SURFACES 

4-inch brick 0.68 

8-inch brick , . . . : .46 

12-inch brick 0.33 

16-inch brick 0.27 

20-inch brick 0.23 

24-inch brick 0.20 

28-inch brick 0.18 

32-inch brick 0.16 

36-inch brick 0.15 

40-inch brick 0.13 

Above is for brick walls not plastered. 



COMMEECIAL PRACTICE IN REGARD TO HEATING BUILDINGS 87 

Heat loss through concrete walls, as given by Mr. W. W. Ma- 
con in Metal Worker, March 11, 1911, is as follows: 

2-inch concrete _. 0.69* 

4-inch concrete 0.55* 

6-inch concrete . 47* 

8-inch concrete . 49 

10-inch concrete 0.35* 

12-inch concrete 0.43* 

16-inch concrete . 37 

20-inch concrete 0.33 

24-inch concrete .30 

28-inch concrete 0.27 

32-inch concrete . 25 

36-inch concrete . 23 

Those marked * are ascribed by Mr. W. W. Macon to Prof. 

Rietschel, and for ordinary construction should be increased 25 
per cent at least. 

Unlined corrugated iron or metal .84 

Corrugated iron or metal over t. and g. boards 0.17 

For roof surfaces : 

Unlined slate 0.82 

Slate over t. and g. boards.- 0.30 

Unlined metal 1 .30 

Iron over t. and g. boards . 17 

Patent roof (tar, gravel, etc.) over t. and g. boards 0.30 

For floors: 

Concrete on ground .30 

Wood close to ground . 10 

Dirt 0.23 

For glass: 

Single window 1 . 20 

Single skylight 1 . 50 

Single monitor 1 . 40 

Double window 0.56 

Double skylight 0.62 



88 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

All the above are for south exposure. Add as follows: 10 per 
cent to the north, east, and west exposure; 10 per cent to the total 
exposure in addition to this if heated in daytime only; 30 per 
cent to the total exposure in addition to the first if heated in day- 
time only and unusually exposed; 50 per cent to the total exposure 
in addition to the first named if heated only at long intervals. 

The loss of heat from galvanized ducts carrying hot air can be 
determined by the formula 

ti — U = 50 S(ti — to), when 

U = temperature of air entering duct. 
t 2 = temperature of air leaving duct. 
t = temperature of air outside of duct. 
S = square feet of surface of duct exposed. 
C = cubic feet of air per hour passing through duct. 

C(h - k) 



The B.t.u. lost per hour = 



55 



MECHANICAL VACUUM SYSTEMS 

These systems are often used on the larger heating installations 
in factories. They are able to reduce the back-pressure on the 
engine to little above atmospheric pressure by removing air and 
condensation by means of a vacuum pump attached to the return 
lines. 

MECHANICAL AIR-REMOVAL SYSTEMS 

These systems are often used in factory work. They are able 
to carry the back pressure on the engines slightly above atmos- 
pheric pressure in that they keep the air removed from the sys- 
tem. 

It may be well to call attention to the fact that with any of the 
vacuum or air removal systems there will always be a back-pres- 
sure on the engines equal to the friction head of the steam in the 
mains; but when the air is quickly and effectively disposed of 
this friction head is comparatively small. 

Example. Let us assume the data for an imaginary building 
and go through the various steps in the design of a factory heating 
system. 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 89 

Assumed data: 

32,100 square feet concrete floor. 
12,250 square feet wall glass. 

6,200 square feet 12 inch brick wall. 

5,400 square feet single skylight. 
31,500 square feet tar and gravel roof. 
710,000 cubic feet contents. 
Steam main 200 feet long. 
Return main 200 feet long. 
Recirculated air. 

Heat to 55° in 0° weather outside. 
Dimensions of building 321 feet x 100 feet x 22 feet. 

Calculations for exposure : 

= 214,000 B.t.u. per hour. 

= 805,000 B.t.u. per hour. 

= 112,000 B.t.u. per hour. 

= 302,000 B.t.u. per hour. 

= 520,000 B.t.u. per hour. 

Contents, 710,000 X 55 4-55 = 710,000 B.t.u. per hour. 

Total = 2,689,000 B.t.u. per hour. 

Add 7.5 per cent for total exposures = 202,000 B.t.u. per hour. 
Add 10 per cent factor safety = 268,900 B.t.u. per hour. 

Total exposure = 3,159,000 B.t.u. per hour. 

Assumed temperature of air at outlets, 120°. 120° — 55° = 
65° which is the drop in temperature of the air called "dif- 
fusion." 65° X .2375 (the specific heat of air at constant pres- 
sure) = 15.4 B.t.u. given off from each pound of air circulated, to 
heat the building. 

3,159,900 ~ 15.4 = 205,000 pounds air per hour to be circu- 
lated by the fan. 

Allow about 10° drop of temperature in the ducts and if a "draw 
through" apparatus is used, as is always preferable, our fan will 
be handling air at 120° + 10°= 130°. 

205,000 pounds per hour X 14.8 -r- 60 = 49,400 C.F.M. handled 
by the fan at 130°. 



Floor, 


32,100 X 


0.30 X 25 


Glass , 


12,500 X 


1.2 X 55 


Wall, 


6,200 X 


0.33 X 55 


Skylight, 


5,400 X 


1.0 X 55 


Roof, 


31,500 X 


0.30 X 55 



90 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

FAN REQUIRED 

Our formula for 8-blades fans is C.F.M. = 0.44 DW. The 
peripheral velocity in factory work with 8-blade fans is usually 
about 5600 feet per minute for factory work. 

Therefore N = 5,600 + t D = 1,785 -i- D and 

C.F.M. = 0.44 X 1,785 D 2 = 786 D 2 from which 
D 2 = C.F.M. -~ 786, substituting, we get 
D 2 = 49,400 -f- 786 = 63 therefore 
D = V 63 = (say) 8 feet. 
N = 5,600 -T- 7r D = 223 Revolutions per minute 

BHP D5N * S - (8)5 X (223)3 X °- 89 - 25 

' ' ' 12,500,000 12,500,000 

ENGINE REQUIRED 

Assumed pressure at the throttle 80 pounds. A 10 x 12 engine 
at this pressure and at 223 R.P.M. will indicate about 32 H.P. 

Sirocco fan required. About 3500 feet per minute is the 
usual peripheral velocity with this style of fan in factory work. 

C.F.M. = 1.1 DW 

But N =^- = 1112 from which is obtained C.F.M. = 1.10 DW 

^ l.li)3xill0 =122()i)2> 

C.F.M. _49400 
1220 1220 " ' 

D = V4L6 = 6J feet = 78 inches. 

AT Ar C.F.M. 49400 ,,«-, , 

BHP - DWS _ (6|) 5 X (164)3 X 0.89 _ 
' ' ' 2,250,000 2,250,000 

Heater. As 205,000 pounds of air per hour are handled by the 
fan and raised from 55°, the temperature of the room, to 130°, 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 91 

the temperature at the outlet of the heater, this will require 
205,000 X 75° X 0.2375 = 3.650,000 B.t.u. per hour. 

Heater. 

Reference to the data on "Vento" heaters will show that for 
5 inch centers standard-depth section with air entering at 50° a 
5-section depth heater would raise the air from 50° to 125° at 
a velocity of about 1400 feet per minute. This is practically 
equivalent to raising air from 55° to 130°, which was the required 
rise of temperature in the case cited. The air quantity, 205,000 

205,000 
pounds per hour, equals 7 = 45,600 C.F.M. at 70 . 

(The Vento curves are based on air volumes, measured at 70°.) 

Now 45,600 -5- 1400 = 32.6 square feet free area in the heater. 

See table of free areas of Vento heaters and note that a heater 
21 sections front, 50 inches high sections and two tiers high would 
have 16.13 X 2 = 32.25 square feet free area and 283J X 10 = 
2830 square feet surface. 

Steam and return piping. 3,650,000 -r- 965 (the latent heat of 
steam at low pressure) = 3800 pounds of steam per hour. The 
formula for steam mains was: 



D= J: 



LW 
Kp 



Substituting L = 200 feet, W = 63 pounds (steam per minute), 
and p = 0.67 pounds, and trying first K = 180, which is assum- 
ing for trial that D will come 6 inches : 



D = V 20 ^ 63 ^ 63 = 6650 = 6 inch diameter. 
M 180X0.67 

For a vacuum system a main 200 feet long to carry 3800 pounds 
of steam per hour should be 7 inches diameter. 

3800 pounds steam per hour -f- 5 sections = 760 pounds per 
hour with pipe coil for each section and 3800 -r- 10 = 380 pounds 
steam per hour with the " Vento" coil, for each group. Referring 
to gravity work the steam connection to each section of 4-row 
pipe coil should be 4 inches and the connection to each group of 
"Vento" coil should be 3| inches diameter. If in the pipe coil 



92 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

the style of section having a " bleeder" connection to the base is 
used use a 2\ inch diameter drip and 1| inch diameter bleeder for 
gravity : 

Vacuum pump. 3,650,000 4-250 = 14,600 square feet equiva- 
lent direct radiating surface. 

3800 pounds -4- 400 = 10 — } inch water-seal motor valves, 

The "pump factor" (10 X 100) + 14,600 = 15,600. Refer to 
table for pump factors and note that a 4J x 6 inch x 8 inch pump 
will be the size to use. 

Proportioning air pipes. Air pipes are usually proportioned by 
the formula: 

N = A I — I in which 



v 



BJ 



A = Diameter of larger pipe. 

B = Diameter of smaller pipe. 

N = The number of pipes of the smaller size to have the 

same " carrying capacity" as one pipe of the larger 

size. 

By " carrying capacity" is meant the amount of air carried, re- 
gardless of velocity, which will give the same loss in pressure due 
to friction per unit of length in each case. 

The diameter of a round pipe to have the same carrying ca- 
pacity as a rectangular pipe of dimensions A and B is given by 
the formula : 

D = 5 I 32 A*B Z 
\^{A + B) 

The method usually followed in laying out factory work is as 
follows: Refer to the equalization table which is applicable for 
either round or square pipes, but not for both at the same time. 
This table gives the number of 1 inch pipes to equal in carrying 
capacity the various sizes given. Thus, if 1 — 12 inch pipe will 
carry a certain amount of air a certain distance with a certain 
loss of pressure due to friction, there would be required 501 — 1 
inch pipes to carry the air the same distance with the same loss 
of pressure, or there would be required 501 -4- 244 = 2 +, pipes 
each 9 inches diameter or say 1 — 9 inch pipe and 1 — 10 inch 
pipe. 



COMMEKCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 93 

Going back to the example and noting that the width of the 
housing is 57 per cent the diameter of the wheel : The outlet of 8- 
blade fans is usually made square with each dimension equal to 
the width of the housing. The fan has a wheel 8 feet = 96 inches 
diameter, X 57 per cent = 54 inches which is one side of the out- 
let, 54 inches X 54 inches = 2916 inches square = pipe 61 inches 
diameter. 

Suppose the fan is set in the roof trusses near the center of the 
building and that is has two outlets, both the same size. From 
the equalization table 1 — 61 inch pipe = 29,000 — 1 inch pipes; 
29,000 -7- 2 = 14,500 — 1 inch pipes; 1—46 inch pipe = 1562 
square inches area = 31 inches x 54 inches, the size of each fan 
outlet. 

The mains should be carried along the roof trusses and the air 
should be discharged about 3 feet above the floor. The branch 
pipes should be carried down along columns, etc., preferably 15 
or 20 feet away from the outside walls and be discharged down- 
ward toward the floor and in the direction of the outside walls. 

Assume it is convenient to take 15 outlets off each 46 inch main 
(which would be about the correct number making them about 
20 feet apart). Each outlet would therefore be 14,500 -f- 15 = 
970 — 1 inch pipes = one 16 inch pipe for each branch. As to 
the size of mains, add the branches together according to the 
equalization table as the fan is approached. Thus, to carry three 
16 inch pipes would require 970 X 3 = 2910 — 1 inch pipes, which 
is equivalent on the equalization table to one 25 inch main. 

By using the fifteen outlets each 16 inch diameter on each 
branch as obtained above, we would perhaps get 10 per cent more 
air out of the outlet nearest the fan than we would from the out- 
let furthest from the fan. This is not a serious error, and it would 
easily be taken care of by adjustments of the dampers; but to 
offset this, and to allow for a cooling of the air before it has reached 
its most distant outlet, it is usual to make the outlets larger as 
we get farther away from the fan. In this case, taking each 46 
inch branch, starting from the center of the building and having 
fifteen outlets, instead of making them each 16 inches diameter 
we would make the four most distant from the fan about 17 inches 
diameter, the next six approaching the fan 16 inches diameter, 



94 MECHANICAL EQUIPMENT OF FEDEBAL BUILDINGS 

and the five nearest the fan 15 inches diameter, adding the branches 
on the equalization table to get the mains. 

The method just given is the one usually followed in factory 
work. There is so much uncertainty in this class of work that it 
seems unnecessary to attempt more refinements. The best ad- 
vice in factory work is to get the fan large enough. If the heater 
is inadequate it is usually a simple matter to add an additional 
section or so of coil, or if you "fall down" on the duct system it is 
often a case of merely making extensions to the piping; and either 
item will cost little more after the system is installed than if put 
in with the balance of the work. 

The most exact method consists in laying out a duct system 
with a certain loss of pressure due to friction, and then designing 
the fan to suit the conditions. Sufficient information on such a 
duct system is given in other parts of this book. Here follows 
the design of a fan, assuming that the duct system is as follows : 

The longest run of duct is : 

Feet 

One-half the length of building = 160 

One-half the width of building = 50 

Drop to floor = 30 

Total =240 

Each fan outlet is 46 inches diameter = 1662 square inches = 
llf square feet. The amount of air through each outlet is 49,400 
^ 2 = 24,700 C.F.M. Velocity in duct = 24,700 + 11J square 
feet = 2150 feet per minute = 36 feet per second. 

As we are using a cone between fan inlet and heater, and have 
not sudden enlargements, we may neglect the entrance head, etc., 
and assume the static pressure to be composed entirely of friction. 

A very safe formula for friction in ducts is as follows : 

LV* 

P = ~ ' when 

25,000 D 

P loss of pressure. in ounces per square inch. 
L = length of galvanized iron duct in feet. 
D = diameter of duct in inches. 

Substituting D = 46 inch, L = 240 feet, and V = 36 feet, we 
have 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 95 

„ 240X36X36 n _ . .. . , 

P = 25,000X46 = ^ ° Z ' = ° M mches W ' g ' 

This is the loss due to friction in ducts. The friction in 24 
rows of 1 inch pipe coil at 1250 feet velocity per minute = 0.65 
w.g. The inlet of the 8-foot wheel would be 96 inches X 0.625 
= 60 inches diameter = 19J square feet. The velocity through 
inlet, which in this case represents the highest velocity in the sys- 
tem, = 49,400 -f- 19J = 2400 feet per minute = 40 feet per sec- 
ond. The pressure necessary to create any velocity is given by 
the formula 

A7 - P - = 8H7Ti60)' inWhich 

A.V.P. = the pressure required in inches w.g. 
V = the velocity per second to be created. . 
t = the temperature of the air handled. 

Substituting in the formula above V = 40, t = 130°, we get 

40 X 40 
A - V - R = 8i (130 + 460) = °' 33 inch6S W - g - 

Inches w.g. 

Duct friction . 46 

Heater friction . 65 

A.V.P .33 

D.P. or dynamic pressure 1.44 

As this is a "draw through" apparatus and the larger part of 
the resistance is on the inlet side, we will use the table for restricted 
inlet. 

A.V.P. -*- D.P. = 0.33 ^ 1.44 = 23 per cent. Refer to table 
and note that when this ratio is 23 per cent the following condi- 
tions will prevail : 

A.V.P.4-P.V.P 20 

D.P.-T-P.V.P 86 

S.P.^P.V.P 66 

K o = 0.55, K a = 3.10, and M.E 54 



96 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

P.V.P. = D.P. -f- 86 per cent = 1.44 -=- 86 per cent = 1.68. 
Referring to the formula given before connecting pressure and 
velocity we get, transposing the formula for velocity: 

Peripheral velocity = V8.5 (130° + 460°) X 1.60 = 92 feet per 
second = 5500 feet per minute. 

The formula for capacity given in the explanation of the table is 

WND 3 ir 
C.F.M. = — — — — ; the symbols being there given. W in this 

case = 0.4D. Substituting, the formula becomes C.F.M. = 
0AND 3 w 

Now DiV = peripheral velocity -5- w = 5500 ^ 3.1416 = 1.750. 

_ 0.4^(1750) _ 2200D* 
C ' KM ' 3J0~~ 3l0~ " 71 ° D * 

Therefore D 2 = C.F.M. 4- 710 = 49,400 4- 710 = 70, and D = 
V70 = 8.3 feet = 100 inches. 

Area inlet = — . ° = — — . = 22.65 square feet = 3265 

VDP Vl.44 

square inches = 64| inches diameter. The standard inlet for 
8-foot wheel is 59 inches diameter. 

N = 5500 -f- 8.37T = 211 revolutions per minute. 

Note that our former solution, which we might call approxi- 
mate, gave us an 8-foot diameter wheel at 223 revolutions per 
minute, which, after all uncertain conditions are taken into ac- 
count, is probably as nearly correct as this one. 

POWER REQUIRED 

Brake H.P. = Air H.P. 4- M.E. 

Air H.P. = force in pounds x distance in feet per minute -f- 
33,000. 

Now the distance in feet per minute = velocity per minute = 
C.F.M. -J- area of duct in square feet; and the force in pounds = 
area of duct in square feet X 144 X total pressure in inches w.g. 
-f- (16 X 1.73). Therefore 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 97 

d tt p _CF.M.Xarea duct in square feet X 144 X total pressure 
area duct in square feet X 16 X 1.73 X 33,000 XiW\#. 

C.F.M. X total pressure in inches wg. ,_, . . 
= MK X635Q . This is a general for- 

mula applicable to all kinds of fans, and in our particular case 
substituting M.E. = 54 per cent, C.F.M. = 49,400, and pressure 
= 1.44 inches w.g., we get: 

_ 49400X1.44 
" ' ' 6350X0.54 

By " total pressure" above is meant not the peripheral velocity 
pressure, but the dynamic pressure. 

Many kinds of buildings, by reason of the nature of the work 
carried on in them, or the more or less sedentary occupations of 
the employees, require special treatment. 

Textile mills. Textile mills are generally heated from one side 
of the rooms. The heat flues are brought up in the outside walls, 
being plastered on the inside or lined with fire-clay flue lining. 
There is usually an abundance of exhaust steam for heating, but 
often a considerable quantity of the exhaust steam is used in the 
dye-rooms, etc. As a rule, the air should not be recirculated on 
account of the fine lint which fills it and the comparatively large 
number and sedentary positions of the operatives. About four 
air changes per hour gives the minimum amount of fresh air to 
be put into the rooms. The velocity of air in the vertical flues is 
usually about 900 feet per minute, and the velocity through the 
mill dampers should not exceed 400 feet per minute. Foul-air 
ducts are sometimes provided, but no exhaust fan is necessary. 

Paper mills. In the machine rooms of paper mills the amount 
of air supplied should be about 100 per cent more than is required 
for the heating figured on a B.t.u. basis. This is on account of the 
large amount of moisture given off by the machines in the form 
of steam. 

If all this vapor had to be absorbed by the air, the air quantities 
would be tremendous. There should be a hood over the machine, 
with an exhaust fan connected thereto, the object being to re- 
move the steam before it has had a chance to condense. The 
capacity of this exhaust fan should be about 75 per cent of the 



98 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

total amount of air forced into the room. It is said that there 
are about two pounds of water evaporated for each pound of 
paper made, and that the capacity of an average machine is from 
one to one and a half tons of paper per hour. This, however, is 
a very general rule. 

On account of the rapid deterioration of the galvanized iron 
ducts, they should be made out of iron two gauges heavier than 
the ordinary, should be soldered with as little punching and rivet- 
ing as possible, and should be hung with copper or brass bands. 

Foundries. In foundries a large amount of steam and other 
gases is given off during the pouring stage. Many of these gases 
are heavier than air and will not rise to the roof. There should 
be not less than three changes of fresh air per hour, but under 
suitable circumstances arrangements may be made for recircu- 
lating the air at times when no processes are going on to contami- 
nate it. If possible an exhaust fan should be provided, and a 
disc fan will often answer this purpose. The inlets to this exhaust 
fan should terminate in bell-shaped orifices about three feet above 
the floor line. The hot-air outlets should be about as in an ordi- 
nary factory job, about 15 or 20 feet above the floor. The above 
remarks apply to iron foundries. In some of the large brass 
foundries it seems simply impossible to get anything like satis- 
factory ventilation. The same system is about the best one for 
a brass foundry, but the air quantities should be at least three 
times that given above. The exhaust fan should in either case be 
of about the same capacity of the heating fan. 

Distillery warehouses. In this class of buildings, on account 
of the high specific heat of the spirits which are constantly being 
removed and replaced by fresh goods, the heating proposition be- 
comes somewhat special. Good practice is to increase the ca- 
pacity of both fan and heater about 25 per cent over that required 
for the heating alone. This will usually give pretty close to four 
air changes per hour. Even then, starting up the apparatus when 
the weather is cold, it will be found that several days will be re- 
quired to get the building and contents up to the temperature 
figured on. 

The construction of such a building usually lends itself very 
admirably to heating. Generally parallel brick or concrete walls 
are built about four feet above the ground and about five feet 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 99 

apart for the full length of the building. These walls are used to 
support the racks in which the barrels are piled to the top of the 
building, sometimes forty feet or more high. There are usually 
about three aisles, one on either side and one in the center of the 
building. These aisles are open all the way to the top of the 
building and are the only portions of the building that are floored. 
The spaces under these aisles are used for hot-air ducts. They 
may have a concrete floor unless galvanized iron ducts are run in 
them. In any event the aisle floor just above, which is of wood, 
should be protected by a sheet of galvanized iron or bright tin! 
The air is admitted to the room through heavy cast-iron gratings 
placed in the floor of the outside aisles about 30 feet apart. These 
gratings must be extra-heavy, as a truck with a barrel of spirits 
will often pass over them; and they should have a suitable deflector 
placed in the duct below so that a correct distribution of air may 
be assured. Air is always recirculated as there is nothing what- 
ever to contaminate it, the space under the center aisle being 
generally used for this purpose. Similar gratings are arranged in 
this aisle for removing the air, and the total area of gratings should 
be the same as the hot air gratings, which should allow an inlet 
velocity of, say, 500 feet per minute. The entire air system out- 
side the building should be closed tight, and this recirculating 
duct should be carried back to the inlet of the heater coil. An 
exhaust fan system is very seldom necessary, as the ducts are 
usually large, owing to the construction of the building. The 
apparatus is usually placed in a separate building, and the system 
will be very simple and inexpensive if this building can be placed 
at the end of the warehouse so that the fan can draw air directly 
out of the recirculating duct, and a double discharge fan is used 
with one discharge going to each of the hot-air ducts. The ducts 
from fan to warehouse will of course be underground, and are 
constructed usually of brick or concrete. Exhaust steam is sel- 
dom available, and the general practice seems to be to use live- 
steam on the coils at boiler pressure and return this condensation 
to the boiler in the most feasible manner. The engine exhaust is 
connected into a separate section of the coil and this condensation 
is returned to the boiler, through a separate return system. 

Planing mills, etc. In woodworking plants in general there is 
usually ample exhaust steam, so that little would be gained in 



100 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

recirculating the air, except in cost of the heater. Often there 
are exhaust systems carrying out considerable quantities of air, 
and there is usually much opening and closing of large doors, and 
the construction of the building is often rather poor. At least as 
much fresh air should be put into the building as is carried out by 
any exhaust system. 

Railroad round-houses. This is about the most uncertain 
class of buildings in regard to heating. The ventilation is quite a 
serious proposition, the locomotive doors are open half the time 
and often the locomotives have considerable snow on them to be 
thawed off before they can be inspected. These uncertainties put 
the round-house in the "guess" class. 

Never less than ten air changes per hour should be allowed: 
always fresh air. The heating surface should be able to raise this 
amount of air from the outside temperature to about 140° which 
will require as a general rule about 300 to 400 square feet of heat- 
ing surface per stall. 

All hot air should be delivered through underground ducts into 
the locomotive pits. Sewer pipe laid in the usual manner may be 
used for the smaller size ducts. Ducts should be proportioned as 
previously explained. Velocity at outlets into pits should not be 
over 600 feet per minute. In the average round-house each pit 
will take four openings each 20 to 22 inches diameter. About 
one length of pipe may be used as an outlet and behind this an 
"increaser" should be used, for in " equalizing" the fan outlet it 
will generally be found that each of these outlets should be fed 
by a branch from the main about 15 inches or 16 inches diameter. 
A suitable adjustable blast-gate should be set in each outlet to be 
operated from inside the locomotive pit it supplies. 

Ventilators, smoke-jacks, and the opening of doors will give 
ample means for the escape of air. 

Apparatus is usually required to be outside the building, and 
when possible should be located near the center, on the outside of 
the round-house. In case of small round-houses the apparatus 
may be set at the end of the building, but it will often be found 
that with this arrangement there is not sufficient room for the 
main duct from the fan to pass between the footings of the out- 
side wall and the locomotive pits. 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 101 

Systems of exhaust ventilation. Systems of exhaust ventila- 
tion have been mentioned several times in connection with the 
heating question. 

In many kinds of industrial works such as foundries, dye-houses, 
etc.. gases are generated, often times heavier than air, which must 
be removed at once. This can be accomplished satisfactorily 
only by exhaust ventilation. Disc fans may be used for this pur- 
pose where the runs of ducts are short or no ducts at all are 
required. 

When the offensive gases are local to the fixtures, as in dye- 
rooms, kitchens, etc., a hood suspended over the entire fixture the 
top of which is connected to the inlet of the exhaust fan is usually 
the best solution. Where the odors or gases are not local to any 
particular fixtures, as in a foundry, a system of bell-mouthed 
openings with inlets connected to the exhaust fan inlet will be 
found most effective. 

As to the amount of air to be removed, judgment must be dis- 
played. No definite rule can be given, except that the amount of 
air handled should be as great as conditions permit. 

It is best not to blow air into kitchens, toilets, etc., from which 
offensive odors might find their way into other parts of the build- 
ing, but preferably exhaust from them as with exhaust fan pulling 
on them there will be an inrush of air whenever a large opening 
into the room exists. If, however, such rooms are very large, as 
the kitchen in a large hotel, it may be necesary to blow some air 
into the room, but the capacity of the exhaust fan should be at 
least 25 per cent greater than that of the plenum fan. 

Toilet-rooms. For a large number of fixtures iocal ventilation, 
supplemented by a register in the ceiling and another in the side 
wall near the floor, is a good arrangement. The local vent horns 
on closets are usually two to three inches in diameter. Connect 
each local vent full size, and add the pipes according to the equali- 
zation table. 

In hotels and office buildings the private bath rooms are usually 
one above another on the various floors for convenience in making 
plumbing connections. In these rooms where there is but one 
closet it is not the custom to resort to local ventilation, but to 
place about 6 inch x 6 inch lock-face register in the wall just above 



102 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

the closet seat and connect this register in the wall to the main 
exhaust riser passing up the pipe shaft just behind. These vari- 
ous risers are collected at the attic and connected to the exhaust 
fan. 

In fine work is it desirable to have a separate riser from each 
private bath room to the main gathering duct in the attic to pre- 
vent noises passing from one room to another, but this will often 
be found impossible for structural reasons. 

Considerable care must be exercised in determining the size of 
ducts, as they will be somewhat small and the friction is liable 
to be excessive. 

In local, venting, an adj ustable damper should be placed in the 
branch to each fixture and the closets should of course have no 
covers. 

Kitchens, boiler rooms, etc. In kitchens, laundries, boiler 
rooms, etc., the foul air should be removed for the most part by 
hoods placed over the ranges, stoves, etc., and in front of the 
boilers. 

When supplying air to such rooms some care must be exercised 
to see that a blast of relatively cold air is not blown directly to- 
wards a workman. If the system is to be used in winter it may 
be necessary to temper the air slightly. Serious lung affections 
are often the result of working in a blast of air which is cold com- 
pared to the air of the room, and as it feels refreshing, workmen 
are apt to run the risk. 

The writer has observed that when fresh air is supplied to boiler- 
rooms, engine-rooms, kitchens, etc., it must be supplied near the 
floor and exhausted from the top of the room if the system is to 
be a success. 

In hospitals, exhaust fans should in general be provided from 
kitchens, contagious wards, toilets, etc., and in the case of the 
contagious wards the duct from each room should be extended in- 
dependently to the main gathering duct in the attic, so as to re- 
move the remotest possibility of germ-laden air passing through 
the ventilating system into other rooms. Often electrically- 
controlled dampers are desirable in such ducts, arranged to close 
automatically if the fan stops for any reason. Such dampers 
when properly installed will prevent the transfer of air from one 
room to another under all circumstances. 



COMMEECIAL PRACTICE IN REGARD TO HEATING BUILDINGS 103 
THE PLENUM CHAMBER SYSTEM 

This system is used almost universally in schools, hotels, etc., 
where the warming is done by hot air and continuous ventilation 
is desired. 

The fans discharge into a large closed chamber which is divided 
by a horizontal partition into two portions, the upper portion 
being generally used for the hot air and the lower portion for the 
tempered air. 

The cold air is usually taken from the top of the building by 
air shafts built for that purpose. Thence it passes through a 
tempering coil of sufficient capacity to raise the air to about 60°, 
if no washer is used. If an air washer is used the temperature 
should also be raised to about 60°; but the washer will reduce the 
temperature to about 45°, and another section of coil should be 
introduced to raise the air to about 60° before the air enters 
the fan, although this is not often done. 

The use of bypass dampers is discussed under the subject of 
automatic temperature control. 

Thence the air is drawn through the fan and forced over the 
heating coils. Under the heating coil is a bypass without a 
damper. The air which goes through the heater passes into the 
hot air portion of the plenum chamber, and that which goes 
through the bypass passes into the tempered air chamber. The 
temperature of the hot air chamber may vary from 100° to 140°, 
and that of the tempered air chamber from 45° to 70°. 

There is a separate duct leading from this chamber to each 
room, or perhaps several ducts lead to a large room. 

In each duct, at the plenum chamber, a set of mixing dampers 
is installed. Each duct has a full size connection to both the 
hot and tempered air portions of the plenum chamber, and the 
mixing dampers are so arranged that the sum of the openings 
from both portions of the plenum chamber into the duct shall 
remain the same ; and the pressure in the two portions being prac- 
tically equal (as a matter of fact the pressure in the tempered air 
portion is always a little greater than that in the hot air portion 
due to the friction in the heater coil) the same amount of air will 
flow regardless of the positions of the mixing dampers. These 
dampers are usually arranged to swing parallel with each other 



104 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

at all times. Each set of these mixing dampers is connected to a 
motor-valve which is operated by a thermostat located in the 
room supplied by the duct. 

In addition to the mixing dampers which affect the temperature 
of air supplied but not its quantity, there is placed in each duct 
near the plenum chamber a volume damper, the object of which 
is to regulate the amount of air in each duct. 

By-passes under heating and tempering coils are usually made 
about 50 per cent the free area of the coils above them. 

School houses. The boilers operate as a rule on 30 to 40 lbs. 
pressure. The fan is usually driven by a direct-connected low- 
pressure engine operating on boiler pressure. This is decidedly 
the cheapest way of operating the engine, because the exhaust 
steam is used in the heater and it may be said that the steam to 
operate the engine costs nothing, for it is well known that exhaust 
steam is worth nearly as much for heating purposes as live steam. 
When electric power is to be purchased it is entirely possible for 
the electric current to cost as much as the steam to heat the air. 
The cost of the electric current is simply wasted, and that much 
might have been saved. Small vertical engines for driving fans 
are made today that are almost as near "fool proof" as an electric 
motor and requires as little attention. 

The coils are fed direct from the boiler through a pressure- 
reducing valve. The engine exhaust passes through an oil separa- 
tor into the low pressure side of the heating main. Steam pres- 
sure on the heater is about 2 to 3 pounds, or atmospheric. 

The condensation is usually returned to the automatic feed 
pump and receiver by gravity and then to the boiler by the 
pump. Sometimes a system of return traps is used. In this 
case there is generally required one trap below the coils into which 
the water can drain by gravity, and a second trap on top of the 
boiler which receives the discharge from the first tap and returns 
the water to the boiler. The live steam connections to these re- 
turn traps must be made from the high pressure side of the steam 
main. 

Hotels, etc. Generally in buildings of this character there is 
a power plant in the basement, for operating generators, ice 
plant, pumps, etc., and fans are then usually driven by electric 
motors, direct-connected, and the heaters are supplied with steam 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 105 

from the exhaust of the various engines, pumps, etc. There is 
often a variety of uses for exhaust steam, and the pipe lines are 
long; and it will nearly always be found necessary to use some of 
the reliable mechanical vacuum systems. 

Heaters and tempering coils. The heating and tempering 
coils, combined, are usually 16 to 24 rows of pipe deep or equiva- 
lent depth of cast-iron sections. The velocity is usually about 
800 feet per minute. 

Air shaft. The velocity in the air shaft should not exceed 600 
feet per minute. 

Ducts and flues. As a general rule ducts are figured for a 
velocity of 900 to 1200 feet per minute and the vertical flues from 
600 to 900 feet per minute. 

Capacity and power of fans. Formulae for capacity and power 
of fans may be found under cases III and IV, depending upon 
which is applicable. 

Foul air removal. For the removal of foul air vent ducts should 
always be provided. In schools and small office buildings vent 
rises the same size as the hot-air flues should be provided, leading 
directly to the attic where means of escape should be arranged, 
preferably by common ventilators of ample size. As a general 
rule it is not necessary to collect piping systems in the attic. 

In hotels, large office buildings, club houses, etc., the runs of 
both heat and vent ducts are long and tortuous. It is usually 
the case that the foul air is removed through the basement and to 
the outside through exhaust flues provided for the purpose. In 
such cases the foul air ducts may as well be omitted if they are 
expected to remove the foul air without a special exhaust fan for 
the purpose. The subject of exhaust ventilation is hereinafter 
discussed. 

The typical school-room is about 28 x 32 feet, and allowing one 
pupil for each 15 square feet of floor space (the general rule) and 
30 C.F.M. to each pupil, we get 1800 C.F.M. to each room. This 
requires 3 square feet of duct area, and at 300 feet velocity per 
minute 6 square feet of screen area. Often a cloak-room is just 
off the class-room and so located that a screen can be placed in 
the connecting door, allowing the warm air from the class-room to 
circulate through the cloak-room on its way to the foul-air duct, 
which has its inlet at the far end of the cloak-room. This warm 



106 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

air serves the double purpose of ventilating this room and dry- 
ing the children's clothing. 

Avoid such myths as gossamer checks, etc., as occupants of the 
rooms often imagine that they are getting no ventilation when 
these checks are closed (as they usually are), when as a matter 
of fact the air is escaping by more convenient channels than the 
foul air ducts. 

Registers, grilles, etc. As a general rule wire screens made of 
about No. 12 wire, 1-inch diamond mesh, wired in f-inch channels, 
and the whole enameled black after being finished and in place, 
are used in school-rooms. These screens are cheap, present a 
neat appearance, offer the freest possible passage to the air, and 
(so desirable in school-room work) contain fewer corners in which 
dust can find lodgment than any other contrivance. 

In office buildings, etc., register faces are generally used when 
the temperature is controlled automatically. 

As a general rule the bottom of the hot-air outlets should be 
about 8 feet above the floor, blowing straight toward the exposed 
wall. The foul-air outlet should be at the floor line as nearly 
under the hot-air outlet as possible. 

In hotel lobbies, cafes, etc., a system of exhaust outlets for 
summer use is usually desirable at the top of a room. The ducts 
from such outlets may be connected to the same exhaust fan as 
the other vents, and either set of vents may be used by a suitable 
arrangement of dampers. 

Floor registers should usually be avoided, as they are extremely 
unsanitary. However, in school work it is a good plan to put a 
floor register about 48 inches x 60 inches or larger in each entrance 
hall as a "foot warmer." 

THE DOUBLE DUCT SYSTEM 

In this system, which has little to commend it, the plenum sys- 
tem is dispensed with and two ducts, a hot-air duct and a tem- 
pered-air duct, are carried to the base of each vertical flue. The 
arrangement of fan, heater, tempering coil, air washer, by-pass, 
etc., is exactly as explained for the plenum-chamber system. The 
air which goes through the heater passes into the hot-air duct, 
and the air which goes through the by-pass passes into the tem- 
pered-air duct. The hot-air duct, which is usually on top, is 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 107 

large enough to carry the entire amount of air; and the tempered- 
air duct is just below it and is about two-thirds the size of the 
hot-air duct. 

The mixing dampers are installed at the base of each vertical 
flue, instead of at the plenum chamber as in the plenum-chamber 
system. These dampers regulate the temperature of the air de- 
livered to the rooms, but not the quantity. To regulate the 
quantity the usual volume dampers are installed in both pipes 
of each branch from the main. 

The pipes of the system are clumsily arranged and unwieldy. 
One of the double ducts should be on top of the other for conveni- 
ence in making the double connections, and this often takes up 
too much headroom unless the ducts are made very shallow, 
which is objectionable. The dampers are scattered all over the 
building, and it is almost impossible to get this kind of a system 
into a complicated building, such as a hotel. It has, however, the 
advantage of permitting hand control of the temperature with 
continuous ventilation. This hand control is accomplished by 
having a suitable arrangement of levers extending down inside 
the air flue, and so arranged that the positions of the mixing dam- 
pers can be controlled from the various rooms. Of course this 
arrangement is possible only in buildings of the simplest con- 
struction. With the double duct system it is possible to use some 
of the inexpensive and effective systems of automatic tempera- 
ture control, which, as hereinafter explained, are not applicable 
to the plenum-chamber system. 

AUTOMATIC TEMPERATURE REGULATORS 

For a plenum-chamber system the systems of automatic tem- 
perature control working through the agency of compressed air 
or electricity are the only practical ones, compressed air being 
preferable. 

For a double duct system, where the mixing dampers are 
placed at the base of the vertical flues, some of the cheaper systems 
in which the mixing dampers are operated by a lever extending 
down from the thermostat in the room through the vertical flues 
to the mixing damper will probably give satisfaction, if proper 
care is given to the design of the levers and dampers. 



108 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

In the pneumatic systems there are two kinds of thermostats, 
one operating the damper with a gradual motion backward and 
forward, seldom closing it off entirely, and another kind operating 
the damper with a so-called positive motion in which the damper 
is either entirely open or entirely closed. There are arguments 
for and against both systems. 

Tempering coils. With the plenum chamber and double duct 
systems the tempering coils are controlled in the manner herein- 
before described, whether an air washer is used or not. 

Heating coil. As a general rule, automatic control is not pro- 
vided on heating coils, the sections being separately valved for 
hand control. 

Mixing dampers. These dampers are controlled by thermo- 
stats in the various rooms, one thermostat to a room being ordi- 
narily all that is required. The thermostats should be of a type 
that will operate the dampers with a graduated or gradually- 
moving motion. 

Cloth filters. Cloth filters are inefficient, and have greater re- 
sistance than is generally supposed, and their use should be dis- 
couraged. The writer recently observed a case where a new, clean 
filter of the texture of ordinary cheese-cloth was in use, and a ve- 
locity of 1 foot per second through same reduced the capacity of 
the fan exactly 25 per cent, all other conditions remaining the 
same during both tests. 

AMOUNT OF AIR FOR VENTILATION 

The following table represents good practice as to the amount 
of air required for the ventilation of various classes of buildings : 

Hospitals 50 to 75 cubic feet per minute per occupant 

High Schools 30 cubic feet per minute per occupant 

College class-rooms 25 cubic feet per minute per occupant 

Theatres, etc .25 cubic feet per minute per occupant 

Churches 20 cubic feet per minute per occupant 

Public waiting-rooms 4 air changes per hour 

Public toilet-rooms 10 air changes per hour 

Locker rooms 6 air changes per hour 

Small convention-hall 4 air changes per hour 

Public offices 3 air changes per hour 

Private offices 4 air changes per hour 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 109 

Ball-rooms 4 air changes per hour 

Public dining-halls 4 air changes per hour 

Banquet halls 5 air changes per hour 

Public libraries 3 air changes per hour 

Private libraries 4 air changes per hour 

Railroad round-houses 12 air changes per hour 

Textile mills 4 air changes per hour 

Foundries 3 air changes per hour 

Hotel lobbies 4 air changes per hour 

Hotel kitchens 4 to 6 air changes per hour 

Boiler-rooms 2 to 6 air changes per hour 

Engine rooms 3 to 6 air changes per hour 

When it is desired to keep the air in a room at a certain stand- 
ard of purity, which is usually expressed in so many parts of C0 2 
per 10,000 parts of air by volume, the amount of air to accom- 
plish this may be estimated as follows : 

It is always necessary to make an assumption as to the amount 
of C0 2 in the outside air. This is usually taken as 4 parts in 
10,000. 

a = number parts of CO2 allowable in the air of room. 

b = number parts of CO2 in external air. 

C = cubic feet of C0 2 per hour to be dissipated. 

Cubic feet of fresh air per hour = [C -4- (a — &)] X 10,000. 

a = about 7 J in schools. 

b = about 4 in ordinary external air. 

C = about 0.6 cubic foot per hour per person. 

RELATIVE TEMPERATURES 

In contract work a guarantee is generally required that the 
plant will heat the building to a certain temperature when the 
outside temperature is a certain degree. As it is usually incon- 
venient to postpone the final tests until the low outside tempera- 
ture named in the guarantee is reached, it is desirable to have 
some means of arriving at results with outside temperature above 
that point. When the plant is tested, if it meets the guarantee, 
the resulting temperature in the rooms will be equal to or greater 
than t 2 given by the following formula : 



110 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

k = [T(t - h) +h(T -t) ^ (T - h), when 
t = inside temperature named in the guarantee. 
h = outside temperature named in the guarantee. 
k = inside temperature maintained during test. 
£3 = outside temperature during test. 
T = temperature of steam or water assumed to be the 
same in test as in guarantee. 

The accuracy of the above formula depends on the following: 
The heat losses from the building are in direct proportion to the 
temperature difference inside and outside; the condensation from 
direct radiation is proportional to the difference in temperature 
of steam or water in the coil and that of the room; and in cases 
of indirect or blast coils the condensation is proportional to the 
difference in temperature of steam or water in the coil and that 
of the entering air. 

There has been considerable argument recently as to the cor- 
rectness of the above hypotheses, without advancing any that are 
more reasonable. 

One reason for a plant in a newly constructed building failing 
to produce the expected temperature may be that so large a part 
of the heat given off by the coils is taken up in drying out the 
brickwork, etc. This is especially noteworthy in concrete build- 
ings. 

In making the test the boilers should be run on the guaranteed 
pressure; and in case of fan work the dampers should be set to 
give the predetermined distribution of air and the fan should be 
run at the specified speed with all vent ducts open. 

COSTS 

The following table gives figures by which a rough preliminary 
estimate may be made of the approximate cost of a job. All ap- 
paratus given is erected complete. 

Steel plate fans: 

1J cents per C.F.M. for factories with foundations. 
1J cents per C.F.M. for schools, etc., with foundations. 
Engines (direct-connected) : 

1 cent per C.F.M. for factories including foundations. 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 111 

If cents per C.F.M. for schools, etc., including foundations. 

Plenum chambers, f to 1 cent per C.F.M. 

Heating surface (iron pipe or cast iron) , 40 cents per square 

foot of surface. 
Galvanized iron work, 10 to 12 cents per pound. 
Registers, If cents per C.F.M. 
Register faces, 1 cent per C.F.M. 
Boilers and piping, $1.50 per square foot indirect surface, 

and 50 cents per square foot direct surface. 
Miscellaneous steam specialties, 2 cents per C.F.M. 
Contractor's profit and miscellaneous expenditures, add 

one-third of total of above. 

PROPERTIES OF FANS 

The object of discussing this subject is not to advocate special 
fans, but to enable the engineer to choose a fan to do a certain 
work when the conditions are known, but are too far out of the 
ordinary to permit the use of the general formulae given in other 
parts of this book. 

An example will be given for each style of fan discussed, and a 
different set of conditions will be assumed in each case to illustrate 
the elasticity of the tables. 

Steel plate fans. These are the ordinary type of eight or ten- 
blade fans, in which: 

Diameter of. inlet =0.61 diameter of wheel. 
Width of periphery = 0.40 diameter of wheel. 
Width of housing =0.54 diameter of wheel. 

In the following table the symbols are as follows : 

A.V.P. = pressure due to actual velocity of air at inlet or 
outlet, called "air velocity pressure." 
S.P. = total friction loss in entire system, i.e., heater, 
washer, ducts, etc., called " static pressure." 
This must also include all loss of pressure due 
to any cause, as sudden enlargement in ducts, 
entrance head, etc. This entrance head is not 
always easy to estimate. An open pipe of 



112 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

short length placed in the outlet of a fan 
will show practically no static pressure, but 
place the same pipe on the inlet of the fan 
and a considerable static vacuum will be 
found, which is the entrance head. This 
head depends, of course, on size of pipe, ve- 
locity of air flow, and the condition of the 
free end of the pipe. A cone in the end will 
reduce this head and increase the air flow, etc. 
Each case in this respect will have to be fig- 
ured out on its own merits, reference being 
had to the various handbooks which contain 
data not necessary or desirable to reproduce 
here. In the tables based on free inlets and 
restricted outlets, the entrance head into the 
inlet is not to be considered, as it has been 
taken account of in the tables. 
D.P. = dynamic or total pressure = A.V.P. plus S.P. 
M.E. = mechanical efficiency. 
P.V.P. = pressure due to velocity of air if it is moving at 
same velocity as fan tips, called " peripheral 
velocity pressure ." 

All pressures are in inches water gauge. The "ratio of open- 
ing" is in fact an arbitrary term. Experimentally, it is the ratio 
of the area of a circular opening in a flat plate close to the fan, and 
through which it discharges, to the area of fan outlet. 

K a = constant for blast area. 

K Q = constant for orifice to be used in the following for- 
mulae : 

Area inlet = -^L; B a = — ; and C.F.M. = wN DW , in which 
VDP Kj K a 

D = diameter of wheel in feet. 
W = width of periphery in feet. 
N = revolutions per minute. 
C.F.M. = cubic feet of air per minute. 
Q = C.F.M. -T- 1000. 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 113 



Pressure of air due to any velocity is 

. TT „ Barometer X V 2 , 

A V r = when 

253(460+0 J 

V = velocity in feet per second, and 
t = temperature of air. 

For a barometer of 29.92 inches mercury, the formula becomes 

72 



A.V.P. = 



8|(460 + 



RATIO OF 
OPENING 


A.V.P. 
D.P. 


A.V.P. 
P.V.P. 


S.P. 
P.V.P. 


D.P. 
P.V.P. 


M.E. 


K a 


K 


per cent 


per cent 


per cent 


per cent 


per cent 


per cent 















117 


117 









10 


1 


1 


116 


117 


15 






20 


2 


1.5 


114 


115.5 


26 


11.3 


2.36 


30 


4 


3.5 


109 


112.5 


35 


7.5 


1.53 


40 


7 


6 


102 


108 


40 


5.7 


1.10 


50 


11 


10 


91 


101 


43 


4.5 


0.87 


60 


15 


13 


78 


91 


45 


3.8 


0.70 


70 


21 


17 


63 


80 


41 


3.2 


0.55 


80 


32 


23 


44 


67 


38 


2-9 


0.46 


90 


52 


28 


23 


51 


31 


2.6 


0.35 


100 


100 


33 





33 


22 


2.3 


0.26 



The above table is based on free inlet and all restriction on the 
outlet side. The " entrance head" into fan inlet is not to be con- 
sidered in using this table. 

For example : Assume we had a heating system in which the 
total friction loss, etc., in heater, washer, ducts, etc., is 1 inch 
water, and that we fix 5000 feet per minute as the velocity of fan 
tips. C.F.M. = 25,000 at 70°, peripheral velocity in feet per 
second = 5000 -*- 60 = 83.3, and 



P.V.P. = 



ss.s- 



Si (460 + 70) 



= 1.54 inches. 



Now S.P. -v- P.V.P. = 1.00 -T- 1.54 = 65 per cent; when this 
ratio exists, by interpolation in the above table we get: Ratio 



114 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

opening = 69 per cent; A.V.P. -f- D.P. = 20 per cent; A.V.P. -s- 
P.V.P. = 16 per cent; D.P. -^ P.V.P. = 83 per cent;' ATA = 
41 per cent; K a = 3.3; and K Q = 0.56. Since we fixed the peri- 
pheral velocity at 5000 feet per minute, irDN = 5000, and since 

n _ . _ TriVDW , nw C.F.M. X X a 25,000 X 3.3 
C .F.M. = — E -,whweDW= 5?0Q0 ■ - 50Q0 - 

16.5, and now, since the usual proportions are W = 0.4 Z>, 
we get 0.4 D 2 = 16.5, or D 2 = 41.25, and D = 6.43 feet = 77 
inches. Use a 6|-foot diameter wheel, as this is a standard size, 
and W = 16.5 + D = 2.54 feet = 30J inches. Now D.P. = 0.83 
P.V.P. = 0.83 X 1.54 = 1.28 inches water, and area inlet = 

= 12.4 square feet = 1780 square inches = 



VD.P. Vl.28 

47J inches diameter, and outlet = 1780 square inches = 42 
inches X 42 inches. 

The brake horse-power is 

_ 5.2XD.P.XC.F.M. _ 5.2X1.28X25,000 
' ' "" 33,000 XII " 33,000X0.41 

Check inlet by A.V.P. = 0.16 P.V.P. = 0.16 X 1.54 = 0.246 
inch, and the velocity to give this pressure is: Velocity = 
V0.246 X (460 + 70) + 8J = 33.3 feet per second = 2000 feet 
per minute, which, divided into the 25,000 C.F.M., gives 12.5 
square feet against 12.4 square feet by the other method. Either 
will be correct. 

N can, of course, be figured by 7rDiV = 5000 and N = 5000 -§- 
irD = 5000 -£■ 6j7r = 245 turns per minute. 

The following table has been calculated from a careful test on 
several 8-blade fans with the outlet practically free and the re- 
striction placed in the fan inlet. It simply means, when com- 
pared with the foregoing table, that a given fan will handle more 
air through a given orifice on the inlet side than it will if the same 
orifice is on the outlet. 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 115 



RATIO INLET 
OPENING 


K a 


A.V.P. 
P.V.P. 


A.V.P. 
D.P. 


D.P. 
P.V.P. 


S.P. 
P.V.P. 


M.E. 


K 


per cent 




. per cent 


per cent 


per cent 


per cent 


per cent 

























fo 


11.60 


1.5 


1 


150 


149 


37 


2.75 


20 


6.00 


5.0 


5 


100 


95 


51 


1.16 


30 


4.55 


9.0 


11 


81 


72 


54 


0.79 


40 ' 


3.75 


13.0 


18 


72 


59 


55 


0.61 


50 


3.10 


20.0 


23 


86 


66 


54 


0.55 


60 


2.80 


24.0 


27 


89 


65 


53 


0.51 


70 


2.55 


29.0 


31 


94 


65 


53 


0.48 


80 


2.45 


32.0 


34 


95 


63 


53 


0.46 


90 


2.35 


34.0 


35 


97 


63 


52 


0.45 


100 


2.30 


36.0 


36 


100 


64 


52 


0.44 



Assume that it is desired to exhaust 25,000 C.F.M, through a 
set of orifices and a pipe in which the friction loss in the pipe plus 
the static head necessary to be maintained just inside the ori- 
fices is 1.1 inches water, and to discharge it into free air at 70° 
temperature; fan to run at about 5000 feet per minute. 

Velocity, 5000 -f- 60 = 83.13 feet per second, and 



P.V.P. = 



(83.3) : 



8J (460 + 70) 



= 1.54 inches; 



and now S.P. -r- P.V.P. = 1.10 -5- 1.54 = 72 per cent, and re- 
ferring to table above, note that: Ratio opening = 30 per cent; 
K a = 4.55; A.V.P. + D.P. = 11 per cent; A.V.P. + P.V.P. = 
19 per cent; D.P. + P.V.P. = 81 per cent; M.E. = 54; K = 
0.79. 

K Q 0.79 X 25 



Area inlet = 



VD.P. Vl.25 



= 17.6 square feet = 2540 



square inches = 57 inches diameter; the D.P., = being 81 per cent 
of P.V.P. = 0.81 X 1.54 = inches 1.25. 

Check inlet by A.V .P. = 0.11 D.P. = 0.11 X 1.25 = 0.137, 
and air velocity = \/0.137 X 8J X 530 = 24 feet per second = 
1440 feet per minute. 25,000 -^ 1440 = 17.4 square feet = 2510 
square inches = 56J inches diameter, which is a good check. 



116 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Assume wheel to be D = 57 -5- 0.61 = 94 inches = 7.83 feet, 
say 8 feet, and N = 5000 -f- 8?r = 200. From the formula 

C.F.M. = — — , we get 

w C.F.M. X K a 25,000 X 4.55 _ 

^ = xjyzy = 5,000 x 8 = 2 ' 85 feet = 34 mches ' 

5.2 X D.P. X C.F.M. __ 5.2 X 1.25 X 25,000 = 
' " 33,000 XM.E. 33,000X0.54 * "" 

In the design of 8-blade fans it should be remembered that if the 
diameter of the inlet is more than two-thirds the diameter of the 
wheel, the blades may be too shallow for maximum efficiency; 
therefore the standard proportions should be adhered to as closely 
as possible. 

Arbitrarily varying the width of the periphery without corre- 
sponding change in size of inlet and outlet will affect the perfor- 
mance but little, so long as the discharge area of the wheel (i.e., 
wDW) is greater than the inlet or outlet area, which is usually 
the case. 

Double-inlet 8-blade fans are constructed in two ways as regards 
their performance with reference to single-inlet fans, discussed 
heretofore. The first method is as follows: If a double-inlet fan 
is to be designed to handle a given amount of air against a given 
pressure, a fan is designed and speed, horse-power, wheel, etc., 
determined for a single-inlet fan to handle one-half the amount 
of air at the given pressure; and then the width of periphery is 
doubled, size of outlet is doubled, and width of housing is increased 
by an amount equal to the increase in periphery. At the same 
speed the fan will handle twice the amount of air handled by the 
single-inlet fan, and will require practically twice the power. 

The second method is to design a single-inlet fan to deliver 71 
per cent of the volume of air required at one-half the static pres- 
sure or friction loss, and then, without changing any dimensions 
of the fan (except adding another inlet of same size) it will do 
the work required without change of speed, and the power will be 
three times that estimated for the single-inlet fan. This is based 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 117 

on a theory, borne out by experiment, that two inlets, without 
any other change in fan or so-called " ratio of opening/' will in- 
crease the capacity of y/ 2 as a multiple, and as the pressure 
varies as the square of the velocity, this will be doubled, and 
further, since the horse-power varies as the product of capacity 
and pressure it will be increased by 2 X 1.41 = 2.82 as a mul- 
tiple, but as there is some loss in efficiency we will call this factor 3. 

The capacity of an 8-blade fan at same speed and same ratio of 
opening varies about as the cube of the inlet diameter; therefore 
to make a double-inlet fan to do the same work as a given single- 
inlet fan, we have merely to divide the diameter of inlet by y/~2 
and use two inlets instead of one. 

In selecting motors or engines for driving fans it is always well 
to be liberal as to sizes. 

Cone fans. The following table gives the properties of the ordi- 
nary type of 8-blade cone fan. The usual proportions are: W = 
0.25 D, and diameter of inlet = 0.75 D. This table is based on 
free outlet and a vacuum chamber on inlet side in which S.P. is 
the total static vacuum in chamber necessary to overcome friction, 
entrance head, etc. 



BATIO OF 
OPENING 


A.VP. 
D.P. 


A.VP. 
P.V.P. 


S.P. 
P.V.P. 


D.P. 
P.V.P. 


M.E. 


K a 


K 


per cent 


per cent 


per cent 


per cent 


per cent 


per cent 















88 


88 









10 


3 


2 


77 


79 


37 






20 


6 


4 


69 


73 


43 


2.9 


1.15 


30 


9 


6 


64 


70 


46 


2.3 


0.90 


40 


13 


11 


58 


69 


48 


1.7 


0.66 


50 


17 


14 


54 


68 


49 


1.5 


0.58 


60 


22 


19 


49 


68 


50 


1.3 


0.51 


70 


28 


22 


45 


67 


50 


1.2 


0.46 


80 


34 


24 


41 


65 


50 


1.15 


0.44 


90 


39 


26 


38 


64 


50 


1.1 


0.42 


100 


45 


29 


34 


63 


50 


1.0 


0.38 



Assume we were exhausting 15,000 C.F.M. through a 36-inch 
diameter pipe in which the friction loss and entrance head are es- 
timated to be 0.50 inch water. Temperature of air 70°. Sup- 



118 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

pose we wanted to use a fan to run at a peripheral velocity of 
about 4400 feet per minute = 73J feet per second. 

P - F - P -=8|W0= L20incheS - 

Now S.P. + P.V.P. = 0.50 4- 1.2 = 0.42 per cent, and from 
the table we find: Ratio of opening = 77} per cent; A.V.P. ■*- 
D.P. = 33 per cent; A.V.P. ^ P.V.P. = 23J per cent; D.P. -r- 
P.V.P. = 65} per cent; -M.#. = 50 per cent; K a = 1.16; and K Q 
= 0.44. 

From C.F.M. = — — — we get 
_ w C.F.M. X X 15,000 X 1.16 Q QA , . _ 

-CW = 7F7^ = 777^ = 3 -96, and smce ^ = 

ttND 4400 

0.25D, we get D 2 = 3.96 ^ 0.25 = 15.7, and D = say 4 feet. 

Now D.P. = 65} per cent P.V.P. = 0.655 X 1.2 = 0.78 inch; 
and A.V.P. = 23} per cent P.V.P. = 0.235 X 1.2 = 0.28 inch. 

5.2 X P.P. X C.P.ilf. _ 5.2 X 0.78 X 15,000 _ 
* 33,000 XM.E. 33,000X0.50 

Area inlet = _^L= = °' U ^} 5 = 72 .2 square feet = 1040 
VD.P. V0.78 

square inches = 36} inches diameter. 

Check inlet by air velocity = \/ A.V.P. X 8} X 530 = 
V0.28 X 8} X 530 = 35.4 feet per second = 2125 feet per min- 
ite, which, divided into 15,000 =7.1 square feet = 1020 square 
inches = 36 inches diameter against 36} inches above. Use 36- 
inch diameter inlet, 48-inch diameter fan, 12 inches wide, and 
R.P.M. = 4400 + 4tt = 350. 

The following table is given for same type of cone fan as above, 
except that all resistance is on the outlet, as for a fan drawing 
free air and discharging into a plenum chamber, the S.P. being 
the static pressure in plenum chamber to overcome friction, en- 
trance head, etc. The ratio of opening is with respect to the 
inlet. All symbols the same as before. 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 119 



KATIO OF 


A.V.P. 


A.V.P. 


S.P. 


D.P. 


M E 


K„ 


K 


OPENING 


D.P. 


P.V.P. 


P.V.P. 


P.V.P. 




■"-a 


-"-o 


per cent 


per cent 


per cent 


per cent 


per cent 


per cent 















105 


105 









10 


2 


2 


91 


93 


51 


3.9 




20 


5 


3.5 


79 


82.5 


49 


3.0 


1.28 


30 


7 


5 


69 


74 


43 


2.5 


1.00 


40 


11 


6.5 


59 


65.5 


39 


2.2 


0.82 


50 


14 


8 


52 


60 


36 


2.0 


0.72 


60 


17 


10 


46 


56 


34 


1.8 


0.63 


70 


21 


11 


42 


53 


33 


1.7 


0.58 


80 


23 


12 


38 


50 


32 


1.6 


0.53 


90 


24 


12 


35 


47 


31 


1.6 


0.51 


100 


26 


13 


31 


44 


31 


1.6 


0.50 



Assume we had a heater, ducts, etc., on the outlet of fan in which 
friction loss and entrance head had been estimated at 1 inch water, 
20,000 C.F.M. at 0°. What size fan is to be used if the peripheral 
velocity is to be 6000 feet per minute, or 100 feet per second? 



P.V.P. = 



(100) 2 
8i (460) 



= 2.56 inches, and 



S.P. 



1.00 



P.V.P. 2.56 



= 39 per 



cent. 

Refer to the table, and note that: Ratio of opening = 78 per 
cent; A.V.P. ^ D.P. = 23 per cent; A.V.P. ^ P.V.P. = 12 per 
cent; D.P. -f- P.V.P. = 51 per cent; M.E. = 32 per cent; K a 
= 1.6; and K G = 0.54. 

A.V.P. = P .V.P. X 0.12 = .12 X 2.56 = 0.308 inch; and air 
velocity = Vo.308 X 8J X 460 = 34.6 feet per second = 2175 
feet per minute; 20,000 -5- 2175 = 9.2 square feet = 1325 square 
inches = 42-inch diameter inlet. 



Check inlet by the formula, Area inlet = 



K Q 0.54 X 20 
VDJP.~ Vi731 



9.25 square feet = 1335 square inches = 42-inch diameter inlet. 

The D.P. being 51 per cent of P.V.P. = 0.51 X 2.56 = 1.31 

inches. Since irDN = 6000, we may find DW by the formula. 



ttNDW= C.F.M. X K a ,from which we get, DW = 



C.F.M. X K £ 



TV. 



ND 



120 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



= 5.33; and since W = — — we 

4 



D 2 
get — = 5.33, or 



20,000 X 1.6 
6,000 

D 2 = 21.3, and D = 4.6 feet = 55 inches. 

Make D = 54 inches, and 42-inch diameter inlet. N = 6000 -*- 
wD = 6000 -T- ( 7rX 4J) = 425 revolutions per minute. 



B.H.P. = 



5.2 X D.P. X C.F.M. 5.2 X 1.31 X 20,000 



13. 



33,000 X M.E. 33,000 X 0.32 

"Sirocco" fans. The following tables give the properties of 
"Sirocco" fans under different conditions of outlet restriction. 
The symbols are as follows : 

A.V.P. = air velocity pressure at fan outlet. 

S.P. = static pressure = total friction loss plus loss of 

pressure due to any other cause. 
D.P. = dynamic or total pressure = A.V.P. + S.P. 
M.E. = mechanical efficiency. 

All pressures are in inches water. 

The ratio of opening is with respect to the fan outlet. Tem- 
perature of air handled is 62° F. The standard proportions of 
"Sirocco" fans are: Width of periphery = one-half diameter of 
wheel, outlet is square and each side = two-thirds diameter of 
wheel, the diameter of inlet in the casing is 1 inch to 2 inches 
larger than the wheel, tapering in a cone to the inlet in wheel, 
which is equal to the diameter of the wheel less the depth of the 
blades. 



o g 


> 
< 




3x 




DYNAMIC OR TOTAL PRES 


SURE-INCHES WATER 






K S 
O 




0.25 


0.375 


0.50 


0.625 


0.75 


0.875 


1.00 


1.25 


1.50 


1.75 


2.00 


Per 






























cent 




1 


C.F.M. 


2000 


2450 


2820 


3164 


3467 


3744 


4000 


4475 


4903 


5295 


5660 


100 


1.000 


0.528 < 


S.P. 
R.P.M. 



303 



371 




428 




478 




525 




567 



605 




677 




741 




801 



864 






I 


B.H.P. 


0.149 


0.274 


0.422 


0.591 


0.776 


0.979 


1.193 


1.670 


2.195 


2.767 


3.382 






f 


C.F.M 


1790 


2194 


2534 


2836 


3105 


3352 


3585 


4013 


4390 


4740 


5068 


95 


0.802 


0.555 I 


S.P. 


0.050 


0.074 


0.099 


0.124 


0.149 


0.173 


0.198 


0.248 


0.297 


0.347 


0.396 


R.P.M. 


296 


363 


419 


469 


513 


554 


592 


661 


726 


783 


838 






[ 


B.H.P. 


0.127 


0.233 


0.360 


0.503 


0.661 


0.832 


1.017 


1.423 


1.868 


2.353 


2.875 






f 


C.F.M. 


1609 


1970 


2275 


2544 


2788 


3010 


3218 


3596 


3940 


4255 


4550 


90 


0.647 


0.578^ 


S.P. 


0.088 


0.133 


0.177 


0.221 


0.255 


0.309 


0.353 


0.441 


0.529 


0.618 


0.707 


R.P.M. 


292 


357 


413 


461 


506 


546 


584 


653 


716 


773 


826 






I 


B.H.P. 


0.110 


0.201 


0.310 


0.434 


0.570 


0.718 


0.878 


1.225 


1.610 


2.029 


2.480 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 121 





J g 




Q 


« 5 

o fa 

a fa 


DYNAMIC OR TOTAL PRESSURE-INCHES WATER 


O 




0.25 


0.375 


0.50 


0.625 


0.75 


0.875 


1.00 


1.25 


1.50 


1.75 


2.00 


Per 
;en< 




f 


C.F.M. 


1451 


1777 


2050 


2295 


2512 


2715 


2900 


3243 


3555 


3840 


4105 






0.590 < 


S.P. 


0.118 


0.178 


0.237 


0.296 


0.355 


0.415 


0.474 


0.592 


0.711 


0.829 


0.948 


85 


0.526 


R.P.M. 


290 


355 


410 


458 


502 


541 


579 


648 


710 


766 


819 








B.H.P. 


0.097 


0.178 


0.274 


0.383 


0.503 


0.734 


0.775 


1.082 


1.423 


1.794 


2.191 








C.F.M. 


1305 


1597 


1845 


2063 


2258 


2440 


2610 


2920 


3195 


3450 


3690 


80 


0.426 


0.595 < 


S.P. 


0.144 


0.216 


0.268 


0.359 


0.431 


0.503 


0.575 


0.718 


0.862 


1.006 


1 . 150 


R.P.M. 


288 


353 


407 


455 


499 


539 


576 


644 


706 


782 


814 






I 


B.H.P. 


0.086 


0.159 


0.245 


0.342 


0.448 


0.566 


0.692 


0.967 


1.27 


1.599 


1.955 








C.F.M. 


1179 


1442 


1666 


1863 


2040 


2205 


2358 


2635 


2888 


3120 


3335 




0.347 


0.590.< 


S.P. 


0.163 


0.245 


0.327 


0.408 


0.490 


0.572 


0.653 


0.816 


0.980 


1.143 


1.306 


75 


R.P.M. 


288 


353 


407 


455 


499 


539 


575 


644 


705 


762 


814 






I 


B.H.P. 


0.079 


0.144 


0.222 


0.311 


0.408 


0.515 


0.630 


0.880 


1.157 


1.458 


1.780 








C.F.M. 


1071 


1312 


1515 


1693 


1855 


2005 


2143 


2395 


2625 


2840 


3030 


70 


0.287 


0.581 < 


S.P. 


0.178 


0.268 


0.357 


0.446 


0.535 


0.624 


0.713 


0.891 


1.07 


1.248 


1.426 


R.P.M. 


290 


355 


410 


459 


502 


542 


580 


64$ 


709 


706 


819 






I 


B.H.P. 


0.073 


0.133 


0.205 


0.287 


0.377 


0.476 


0.581 


0.812 


1.068 


1.348 


1.643 








C.F.M. 


980 


1200 


1386 


1550 


1698 


1833 


1960 


2192 


2402 


2593 


2773 


65 


0.240 


0.567 < 


S.P. 


0.190 


0.285 


0.380 


0.475 


0.570 


0.665 


0.76 


0.95 


l. v 14 


1.33 


1.52 


R.P.M. 


293 


359 


414 


463 


507 


548 


586 


655 


718 


775 


828 






I 


B.H.P. 


0.068 


0.125 


0.193 


0.269 


0.354 


0.446 


0.545 


0.761 


1.001 


1.26 


1.539 






■ 


C.F.M. 


895- 


1096 


1265 


1414 


1550 


1674 


1790 


2000 


2193 


2367 


2530 


60 


0.200 


0.548 < 


S.P. 


0.20 


0.30 


0.40 


0.50 


0.60 


0.70 


0.80 


1.00 


1.20 


1.40 


1.60 


R.P.M. 


298 


264 


421 


471 


516 


557 


595 


665 


729 


788 


842 






I 


B.H.P. 


0.064 


0.118 


0.182 


0.254 


0.334 


0.421 


0.515 


0.719 


0.946 


1.19 


1.454 






■ 


C.F.M. 


813 


996 


1150 


1285 


1408 


1520 


1625 


1818 


1990 


2150 


2300 


55 


0.165 


0.531 < 


S.P. 


0.209 


0.313 


0.417 


0.522 


0.626 


0.731 


0.835 


1.044 


1.253 


1.461 


1.670 


R.P.M. 


302 


371 


428 


479 


525 


566 


605 


677 


741 


800 


855 






I 


B.H.P. 


0.06 


0.111 


0.171 


0.238 


0.313 


0.395 


0.482 


0.674 


0.887 


1.116 


1.365 






f 


C.F.M. 


729 


892 


1030 


1151 


1261 


1361 


1457 


1628 


1783 


1927 


2060 


50 


0.133 


0.517 < 


S.P. 


0.217 


0.325 


0.434 


0.542 


0.651 


0.759 


0.868 


1.084 


1.301 


1.518 


1.735 


R.P.M. 


305 


373 


431 


482 


528 


570 


609 


681 


747 


807 


862 






I 


B.H.P. 


0.055 


0.102 


0.157 


0.219 


0.288 


0.363 


0.444 


0.620 


0.815 


1.026 


1.254 








C.F.M. 


643 


787 


910 


1015 


1112 


1202 


1285 


1435 


1572 


1700 


1818 


45 


0.103 


0.503 < 


S.P. 


0.224 


0.336 


0.448 


0.561 


0.673 


0.785 


0.897 


1.121 


1.345 


1.57 


1.794 


R.P.M. 


305 


373 


431 


482 


529 


550 


610 


681 


748 


807 


863 








B.H.P. 


0.050 


0.093 


0.142 


0.199 


0.261 


0.33 


0.402 


0.562 


0.740 


0.903 


1.139 








C.F.M. 


566 


694 


800 


895 


981 


1059 


1131 


1265 


1386 


1497 


1600 


40 


0.080 


0.490 < 


S.P. 


0.23 


0.345 


0.460 


0.575 


0.6S0 


0.805 


0.920 


1.150 


1.380 


1.610 


1.840 


R.P.M. 


304 


372 


430 


481 


526 


569 


609 


681 


745 


805 


860 






{ 


B.H.P. 


0.046 


0.084 


0.129 


0.180 


0.237 


0.298 


0.364 


0.509 


0.669 


0.843 


1.029 








C.F.M. 


426 


523 


604 


675 


740 


799 


854 


955 


1046 


1129 


1.209 


30 


0.046 


0.451 < 


S.P. 


0.239 


0.358 


0.477 


0.597 


0.716 


0.835 


0.955 


1.193 


1.432 


1.670 


1.909 




R.P.M. 


298 


366 


423 


472 


513 


559 


597 


668 


732 


790 


845 






[ 


B.H.P. 


0.037 


0.069 


0.105 


0.147 


0.194 


0.244 


0.298 


0.417 


0.548 


0.689 


0.844 








C.F.M. 


290 


355 


410 


458 


502 


543 


580 


640 


711 


768 


820 


20 


0.021 


0.352 < 


S.P. 


0.245 


0.367 


0.490 


0.612 


0.734 


0.857 


0.979 


1.224 


1.468 


1.713 


1.958 


R.P.M. 


288 


353 


407 


455 


499 


539 


575 


644 


705 


762 


814 








B.H.P. 


0.032 


0.060 


0.092 


0.128 


0.169 


0.213 


0.260 


0.363 


0.478 


0.602 


0.724 






[ 


C.F.M. 


167 


205 


237 


265 


290 


313 


335 


374 


410 


443 


480 


10 


0.007 


0.212 < 


S.P. 
R.P.M. 


0.248 
273 


0.372 
334 


0.497 

386 


0.621 

432 


0.745 

473 


0.869 
511 


0.993 
546 


1.241 
610 


1.490 

670 


1.738 
723 


1.986 

773 






[ 


B.H.P. 


0.031 


0.057 


0.088 


0.123 


0.162 


0.204 


0.249 


0.348 


0.457 


0.576 


0.714 



122 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

The following table gives certain factors varying with size of 
fan wheel. 



WHEEL 


VOLUME AND 
B.H.P. CONSTANT 


R.P.M. 

CONSTANT 


SIZE OF OUTLET 


Number 


Diameter 






inches 






inches 


1 

2 


3 


0.0278 


6.00 


2x2 


3 
i 


4i 

^2 


0.0625 


4.00 


3x3 


1 


6 


. 0.1111 


3.00 


4x4 


H 


7 1 - 

« 2 


0.1736 


2.40 


5x5 


i* 


9 


0.2500 


2.00 


6x6 


if 


10| 


0.3403 


1.714 


7x7 


2 


12 


0.4444 


1.500 


8x8 


2i 


15 


0.6944 


1.200 


10x10 


3 


18 


1.000 


1.000 


12x12 


3| 


21 


1.3611 


0.857 


14x14 


4 


24 


1.7778 


0.750 


16x16 


^2 


27 


2.2500 


0.667 


18x18 


5 


30 


2.7778 


0.600 


20x20 


6 


36 


4.000 


0.500 


24x24 


7 


42 


5.444 


0.429 


28x28 


8 


48 


7.1111 


0.375 


32x32 


9 


54 


9.000 


0.333 


36x36 


10 


60 


11.111 


0.300 


40x40 


11 


66 


13.444 


0.273 


44x44 


12 


72 


16.000 


0.250 


48x48 


13 


78 


18.778 


0.231 


52x52 


14 


84 


21.778 


0.214 


56x56 


15 


90 


25.000 


0.200 


60x60 


16 


96 


28.444 


0.188 


64x64 


17 


102 


32.111 


0.176 


68x68 


18 


108 


36.000 


0.167 


72x72 


19 


114 


40.111 


0.158 


76x76 


20 


120 


44.444 


0.150 


80x80 


21 


126 


49.000 


0.143 


84x84 


22 


132 


53.778 


0.136 


88x88 


23 


138 


58.776 


0.130 


92x92 


24 


144 


64.000 


0.125 


96x96 



Example: Assume it be required to force 32,000 C.F.M 
through a 48-inch X 48-inch duct in which friction loss, etc, is 
1-inch water gauge, using a 72-inch diameter wheel which has an 
outlet 48 inches x 48 inches. Temperature of air 62° — Air ve- 



COMMERCIAL PRACTICE IN REGARD TO HEATING BUILDINGS 123 

locity = 32,000 -f 16 = 2000 feet per minute = 33J feet per 

second. 

3312 

A ' V ' P ' = 8| (460 + 62) = °' 25 incheS ' 

D.P. = S.P. + A.V.P. = 1.00 + 0.25 = 1.25 and 
A.V.P. 4- D.P. = 0.25 ^ 1.25 = 20 per cent. 

In the table note that the ratio of opening is 60 per cent, and 
when D.P. = 1.25 inches the C.F.M. = 2000; S.P. = 1.00; 
R.P.M. = 665; and B.H.P. = 0.719. Multiplying these quan- 
tities by the factors taken from the table above we get: C.F.M. 
= 2000 X 16 = 32,000; B.H.P. = 0.719 X 16 X 11.5; and .R.P.M. 
= 665 X 0.25 = 166 to do the work assumed. 

"Sirocco" fans are made double-inlet, double-width wheel, 
double-width casing, and double-size outlets, which, of course, 
have twice the capacity and twice the power of single-width fans 
at the same pressure. The tables above refer to single-width 
fans. 

Should pressures higher than those given in the table be en- 
countered, the quantities can be calculated by the fact that the 
C.F.M. and R.P.M. vary directly as the square root of the dyna- 
mic pressure; that static pressure varies directly as the dynamic 
pressure; and the B.H.P. varies directly as the product of dyna- 
mic pressure and C.F.M. For example : Assume 70 per cent ratio 
of opening, 2.5 inches D.P. Find C.F.M., S. P., and B.H.P. 
At 2 inches D.P. the C.F.M. = 3030; S.P. = 1.426; R.P.M. = 
819; and B.H.P. = 1.643. 

Now 2.4 ^ 2.0 = 1.25, and \/L25 = 1.12. The new C.F.M. 
= 3030 X 1.12 = 3388; the new S.P. = 1.426 X 1.25 = 1.782; 
the new R.P.M. = 819 X 1.12 = 916; and the new B.H.P. = 

1.643 X 2.5 X 3380 _ 

2.0 X 3030 ' " 

Of course these new quantities are subject to correction ac- 
cording to size of wheel, the same as quantities taken directly 
from the table. 

The table can also be interpolated bv the method above given. 



CHAPTER III 

HEATING BY FORCED CIRCULATION OF HOT WATER FROM A 

CENTRAL STATION 

Heating from a central plant is most common in localities where 
the general run of buildings are not of sufficient size to justify the 
expense of private plants; and even where no exhaust steam is 
available and all the heating is done directly from the coal, a 
saving in cost of labor and fuel is effected. 

In generating stations where the electrical energy is used in 
lighting the buildings, the utilization of the exhaust steam from 
the power units results in a marked degree of economy. 

Requisites for successful operation. The power plant would be 
located as near as possible to the center of gravity of the district 
served, to avoid excessive loss of heat in the underground transmis- 
sion lines, and there must be a large connected heating load. A 
large plant should be located on a railroad siding or by a navi- 
gable river to insure economical delivery of coal, and a plentiful 
supply of good water must be available. 

Advantages of hot water over steam, where condensing engines 
or turbines are used. With condensing engines the water heaters 
are placed between the engines and condensers, and heat that 
otherwise would be thrown away in the condenser overflow is 
utilized, and a saving effected in amount of condenser water. 

Less heat is dissipated by radiation from the piping with water 
at an average temperature of 160° than with steam at 212°, and 
hot water is best adapted to undulating ground, the mains follow- 
ing the contour of the surface, and branch mains or surface con- 
nections being taken off at the highest points to prevent the 
formation of air pockets. 

Economy of operation with hot water is not dependent upon 
the adjustment of delicate parts, such as thermostats, etc., and 
the same efficiency is maintained year after year. • 

Regulation. With all systems of heating the radiating surface 
is proportioned to obtain the desired room temperature with 

124 



HEATING BY FORCED CIRCULATION 



125 



minimum outside temperature and with all radiation in use. 
Steam as the heating medium (unless a vacuum system is used) 
must entirely fill the system at a temperature of 212°, requiring 
a large amount of heat. The average outside temperature dur- 
ing the usual heating season of 200 days is 35°F., hence on the 
majority of days only a small amount of heat is required, and hot 
water will distribute this evenly throughout the entire system. 
Thermostatic control and vacuum systems give close regulation 
for steam, but these devices generally require careful adjust- 
ment, with frequent inspection to maintain efficiency, while hot 
water, regulated from the power house, has been found to be very 
satisfactory without automatic temperature control. The tem- 
perature of the circulating water is proportioned to suit varying 
weather conditions, and the following temperatures of circulating 
water have been found to be satisfactory: 



TABLE I 



TABLE II 



"WITH OPEN EXPANSION TANK 


WITH CLOSED 


EXPANSION TANK 


Outside 
Temperature 


Water 
Temperature 


Outside 
Temperature 


Water 
Temperature 


degrees F. 


degrees F. 


degrees F. 


degrees F. 


50 


140 


50 


150 


45 


140 


45 


155 


40 


150 


40 


160 


35 


160 


35 


165 


30 


165 


30 


170 


25 


170 


25 


175 


20 


180 


20 


180 


15 


185 


15 


185 


10 


190 


10 


190 


5 


195 


5 


195 





200 





200 


- 5 


205 


— 5 


210 


-10 


210 


-10 


220 


-15 


215 


-15 


230 


-20 


215 


-20 


240 



Limitations of hot water system. Water at 180° weighs 60.5 
pounds per cubic foot and produces a static pressure of 60.5 4- 
144 = 0.42 pound per foot or 42 pounds per square inch per 100 



126 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

feet of head, and this head should rarely be exceeded due to the 
excessive pressure on the pumps, piping, and radiators, and the 
tendency to produce leaks and rupture of joints. 

Quality of material. Selection of materials is determined by 
considerations of efficiency, durability, and first cost, in the order 
named. Quality of materials and workmanship especially in the 
conduit line, should be of the best. 

Conduits. Five to 12 per cent of the total heat transmitted is 
lost by radiation from the distributing mains, and as this creates 
an operating expense which is continuous year after year it should 
be made as small as possible. Where funds are available, con- 
crete tunnels not less than 5 feet inch wide by 6 feet 6 inches 
high should be used to receive the piping, but when funds are 
limited material for the trenches may be wood, tile, brick, and 
concrete. The best and most recent commercial types of conduits 
comprise the use of hollow tile, brick, or concrete walls resting on 
a concrete base, with hollow tile or reinforced concrete covers, 
the whole made as waterproof as possible by a 1-inch layer of 
cement mortar on sides and top. The piping is provided with 
sectional covering of magnesia, asbestos, or wool-felt, or the en- 
tire air space around pipes is packed full of mineral wool, asbestos, 
or magnesia. 

All piping in conduits is supported on pipe rollers. 

Service connections vary from lj to 2 J inches in diameter and 
are laid at an average of 3 feet below the surface of the ground. 
Conduits for service connections should compare favorably with 
the main conduits in quality of materials, though 4-inch thick 
wood log pipe covering, lined with tin or asbestos, is generally 
used and answers every requirement. 

The drainage of conduits is secured through lines of 4-inch tile 
placed at side of foundations, with outflow to sewer or catch basin. 

Expansion. The expansion of wrought iron is 0.00008 of an 
inch per foot per degree rise of temperature, which for a hot- 
water main under ordinary working conditions would equal .013 
inches per foot of length. Experience has shown, however, that 
an increase in length of 1 inch for each 100 feet will approximate 
actual results. 

Offsets made with 90° pipe bends, right-angle turns or expan- 
sion joints spaced from 350 to 500 feet apart, with anchors mid- 



HEATING BY FORCED CIRCULATION 127 

way between are used to take up the expansion. Spacing of 
offsets for district heating in cities is determined by the length of 
blocks, an offset usually being made in. each street crossed by the 
mains. Straight runs of pipe between anchors are laid and se- 
cured in place, and are of such lengths that the last joint to be 
made up in the offset is open an amount equal to one-half the 
computed expansion between adjacent anchors. The drawing 
together of this joint provides a stress in the offset when cold 
equal to that which will be developed when the pipe becomes 
hot. The pipes are offset from 25 to 30 times the diameter of 
pipe, the length of the offset usually being equal to the width 
of the street crossed, and as all turns are made with long-radius 
pipe bends no great amount of friction is introduced by their use. 

A maximum movement of 5 inches is allowed for expansion 
joints which determines the maximum spacing; and they should 
be simple and of the slip-joint type, with cast-iron body, brass 
sleeve, and a type of metallic packing, which may be easily 
renewed. 

Anchors. The spacing of anchors is determined almost en- 
tirely by the conditions governing the location of the devices to 
take up expansion, though in general the mains should be anchored 
at or near each branch and at important service pipes. 

Anchors are of two general types, one integral with the joint at 
which it is used, such as expansion joints or anchor tees bolted 
to the floor of the conduit, and the other in the form of pipe 
bands bolted around the pipe. The latter should be applied on 
each side of a coupling or other fitting to ensure against slippage, 
and should extend at least 9 inches into the brick or concrete 
walls of the conduit. Special piers of brick or concrete are often 
constructed to provide a secure fastening for anchors. 

Valves. Only straight-way gate valves are used, and these are 
placed on the trunk mains at the central plant and at such points 
throughout their length as will allow certain portions of the sys- 
tem to be shut off for repairs without cutting out the entire dis- 
trict; on all the branch mains as they leave the trunk; on all 
by-pass lines; and on all service connections to buildings. 

Manholes. Manholes are placed at all valves on mains and at 
expansion joints, and are constructed of brick or concrete with 
cast-iron frame and cover. Frames should have not less than 



128 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

22 inches diameter clear opening, and joint between frame and 
cover should be practically water-tight. 

Radiation in individual buildings. The heat lost by exposure 
from each building in British thermal units is found by estab- 
lished rules, a temperature 10° above the lowest recorded for the 
locality being used as a basis, and the result divided by 170 will 
equal the square feet of direct cast-iron radiation required. Ra- 
diators are placed under windows where possible, and in the 
basement approved types of wall radiators or wrought-iron pipe 
coils are suspended from the ceiling. 

In many systems now in successful operation a water tempera- 
ture as high as 212° has been used in proportioning the amount of 
radiating surface required for minimum outside weather condi- 
tions, the British thermal units lost from the building being di- 
vided by 250 to find the square feet of direct radiation required, 
since water at 212° will transmit the same amount of heat per 
square foot as steam at the same temperature. During most of 
the heating season the outside temperature is considerably higher 
than the minimum for which the radiation is proportioned, and 
the water can be circulated at a temperature of 180° or lower. 
The larger line losses which occur at the higher water temperature 
are thus limited to a few days only of the heating season, and are 
more than compensated by the decrease in size and cost of the 
whole installation. A closed expansion tank is used with this 
system, and for extreme weather conditions the water may be 
circulated at temperatures considerably in excess of 212°. 

Layout of mains. A drawing showing the location of the 
power-house and the buildings to be served should be prepared, 
and the square feet of radiation required or the heat to be sup- 
plied in British thermal units should be noted for each building. 
The mains are then laid out to serve the buildings with the 
shortest possible runs, conduits being run in alleys and unpaved 
streets wherever possible, by reason of the lower cost for installa- 
tion and repairs. Valved by-passes are provided between im- 
portant points, and the main trunk lines are cut as little as 
possible. 

Two systems of mains are in common use, the 1-pipe circuit and 
the 2-pipe circuit. One-pipe mains are used generally where a 
small number of buildings, often at considerable distance apart, 



' 



HEATING BY FORCED CIRCULATION 129 

are to be heated, the water making a complete circuit through a 
single main of a uniform diameter, the service pipes to the in- 
dividual buildings being shunts from the main itself. Individual 
shunts are the same pipe-size from end to end, radiator conuec- 
tions being taken off at necessary intervals and "Y" fittings 
provided where each shunt leaves and returns to the main, to 
induce flow through the building. The supply and return con- 
nections of each shunt are kept as far apart in the main as the 
length of the buildings will allow, to provide sufficient resistance 
to cause the water to flow through the shunt, and a valve is some- 
times inserted in the main between the connections to control 
this resistance. Occasionally the main itself is carried through 
each building, the radiation being supplied by risers from shunt 
circuits of uniform size taken off within the building, a valve 
being placed in the main between supply and return connection 
to shunts to control the flow in same. In individual buildings 
where the radiation will never be shut off, the entering main is 
divided into a number of circuits of radiators in series (the com- 
bined sectional area of the pipe connection being made 50 per 
cent greater than that of the main) which re-unite into a single 
main on leaving the building at the far end. Circulation in low 
buildings may be forced by arranging all the radiation in one or 
more series circuits, tjie return from one coil continuing as the 
supply to the next, between the supply and return service connec- 
tions. In high buildings the water is carried upward through a 
main riser to the distributing main in the attic, thence downward 
through 1-pipe risers to the return mains in basement and out to 
main in street, the circulation in individual radiators being caused 
by gravity only. Radiator connections enter radiator at top and 
leave same at bottom, "Y" fittings or distributing tees ofteQ 
being used to ensure positive circulation. 

Vertical offsets over doors and at all other points where a hori- 
zontal main turns downward are provided with air valves of the 
float type. 

A velocity of flow up to 12 feet per second is maintained in the 
1-pipe mains since the cooled water from one building becomes in 
part the supply water for the next; and as the force producing 
circulation in the service pipes is small, larger sizes are used for 
these than with the 2-pipe system. 



130 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

The 2-pipe system is used for large installations and is best 
adapted to serve contiguous buildings, as in city blocks. Supply 
and return mains of equal size and in same conduit radiate from 
the central plant, with suitable reductions in size as the total out- 
lying radiation becomes less. Circulation in the service pipes and 
mains of individual buildings is caused by the difference in 
pressure between the supply and return mains. 

The size of mains for either system is dependent upon the 
amount of water to be circulated and the velocity of flow, which, 
as previously stated, is made 2 to 3 feet higher per second for the 
1-pipe than for the 2-pipe system. 

Radiator connections. The size of supply and return connec- 
tions to radiators and pipe coils depends upon the force produc- 
ing flow through same, and hence upon the layout of piping and 
connections. 

Radiators dependent entirely upon gravity for circulation are 
tapped according to standard practice for gravity work, the size 
varying with basement mains and overhead mains, and according 
to whether a 1-pipe or a 2-pipe system of risers is used. 

Where the radiators or coils are arranged in series the size of 
pipe for the whole circuit is proportioned according to the amount 
of radiation and the friction loss in the total length of circuit, 
a 2-inch pipe carrying generally from 500 to 700 square feet of 
radiation; and the total area of connections, where a 1-pipe main 
divides into a number of series circuits, is made 50 to 100 per 
cent greater than the area of the main itself. 

Due to the widely varying conditions with different systems 
found in actual practice, the size connections for all except grav- 
ity circulation are largely determined for each individual case 
by the judgment and experience of the designing engineer. 

Water required to be circulated. In estimating a branch from 
a main the assumption is made that the difference in temperature 
between the flow and return pipes is 30°F. Water in cooling 
from 180° to 150° gives up 30 B.t.u. per pound, hence the total 
heat lost per hour from the group of buildings supplied by each 
branch, or contemplated by future extensions to the system, plus 
10 per cent additional for transmission loss, divided by 30 will 
give the pounds of water required for the branch. Water at 
180° weighs 60.5 pounds per cubic foot, hence the pounds of water 



HEATING BY FORCED CIRCULATION 



131 



required divided by this figure will give cubic feet per hour. 
The cross-sectional area, and hence commercial size, of any 
pipe is then found by dividing the total cubic cubic feet per 
hour by 3600 X allowable velocity in feet per second, or 

pounds water per hour ~ 
= Cross sec- 

60.5 X 3600 X allowable velocity in feet per second 

tional area of pipe in square feet. 

The area of trunk mains is found by dividing the total cubic 
feet of water per second from branch mains by the allowable 
velocity of flow. This velocity is ordinarily made from 5 to 10 
feet per second, the smaller values being used for branch connec- 
tions and outlying mains, where they serve to compensate the 
rapid increase in frictional resistance with decrease in diameter of 
pipe. Velocities should be limited to 10 feet per second as a max- 
imum, in connection with the largest amount of radiation contem- 
plated by future extensions to the system, due to the rapid increase 
in friction with increase of speed as shown by Table III, values 

0.32F 1 ' 86 
of which are found by the formula for hot water, h = ' 25 

where h is the loss in friction in feet per 100 feet of length, D is 
the diameter of pipe in feet, and V is the velocity in feet per 
second. 

TABLE III 

Velocity in feet per second 



PIPE SIZE 
IN INCHES 



2 


3 


4 


5 


6 


7 


8 


9 



10 



Friction head in feet per 100 feet of pipe 



2 
3 

4 
5 
6 
7 
8 
9 
10 
12 



1.09 


2.32 


4.06 


0.658 


1.40 


2.45 


0.459 


0.980 


1.70 


0.349 


0.742 


1.29 


0.276 


0.588 


1.03 


0.228 


0.485 


0.848 


0.193 


0.411 


0.717 


0.166 


0.354 


0.617 


0.146 


0.311 


0.541 


0.116 


0.246 


0.431 



6.02 

3.62 

2.52 

1.92 

1.52 

1.25 

1.06 

0.913 

0.800 

0.638 



8.46 


11.25 


14.43 


17.96 


5.08 


6.76 


8.70 


10.80 


3.54 


4.70 


6.04 


7.60 


2.70 


3.57 


4.60 


5.70 


2.14 


2.83 


3.64 


4.53 


1.75 


2.34 


3.00 


3.72 


1.50 


1.98 


2.54 


3.17 


1.28 


1.70 


2,19 


2.72 


1.12 


1.50 


1.93 


2.37 


0.900 


1.19 


1.53 


1.91 



21.88 
13.20 
9.17 
6.97 
5.53 
4.56. 
3.86 
3.33 
2.92 
2.32 



132 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

144 

The friction head in feed divided by — — - or 2.38 becomes the 

oO.o 

head in pounds per square inch. 

Pipe bends instead of fittings are used wherever possible, and 
where runs of pipe between fittings are short, 10 per cent is added 
to the friction loss in the pipe to cover the additional loss in the 
fittings. 

In a well-designed plant with a static head not larger than 45 
pounds, average outflow and return gauge pressures of 65 and 
20 pounds respectively will be found, and the differential pressure 
due to friction between the supply and return mains, which the 
pump must constantly overcome, will vary with the size of instal- 
lation from 25 to 50 pounds, and on account of the tendency to 
produce leaks and rupture of joints should never exceed the last- 
named amount. Pipe sizes should be made large enough to 
assure this. The static heads on suction and delivery sides are 
equal, hence the only work required of the pump is to overcome 
the friction due to the velocity of the moving water in the piping 
system. 

For example, the size supply and return pipe required to carry 
20,000 square feet of radiation, transmitting 170 B.t.u. per square 
foot, at a distance of 100 feet, with a loss in head of 1 foot, and 
water in radiation cooled 30°, is found to be 6 inches as follows : 
20,000 X 170 + 5 per cent line loss = 3,570,000 B.t.u. per hour. 
3,570,000 ^ 30 X 60.5 X 3,600 = 0.546 cubic foot water per 
second. Area of 6-inch pipe = 0.196 square foot, hence 0.546 -r 
0.196 = 2.8 feet per second and from Table III, by interpola- 
tion, the loss of head for 200 feet of 6-inch pipe and velocity of 
2.8 feet per second, is 1 foot, equal to 0.42 pounds, per 200 feet 
of pipe. 

Wlhen buildings can be reached by a circuit with the far end re- 
turning to the power house, there is less friction loss with the 1-pipe 
than with the 2-pipe system, hence the former should be used. 

In 2-pipe work a tabulation of the loss in head for each section 
of main will show the circulating pressure between the supply 
and return mains at any point, and the friction loss in all laterals 
should be proportioned to the circulating pressure at the point 
where the lateral begins. A throttling union, consisting of an 
ordinary union enclosing a hardened steel disc with a round ori- 



HEATING BY FORCED CIRCULATION 



133 



fice in its center, is often installed on each branch return connec- 
tion near the controlling valve, the frictional resistance being 
regulated to the desired amount by varying the size of the opening 
in the disc. This device is particularly useful to prevent short- 
circuiting in branch mains which are installed with excessive ca- 
pacity in contemplation of future extension. 

A circulating pressure of at least one pound should be maintained 
at end of each branch. 

Table IV gives average values for the drop in pounds per 100 
feet of flow and return main, per 1,000 square feet of radiation 
with the commercial sizes of pipe up to 10 inches. Average 
velocities are used, increasing as the pipe size becomes larger, 
and due consideration is given to the fact that, with a 2-pipe 
system having branch connections at frequent intervals, from 50 
to 70 per cent only of the total volume of water is transmitted 
the full 100-foot lengths, the friction being correspondingly 
decreased. 

TABLE IV . 



RADIATING SURFACE 










PIPE SIZE IN 


INCHES 










IN SQUARE FEET 


2 


3 


31 


4 


5 


6 


7 


8 


9 


10 


12 


1,000 


0.50 

1.10 
2.50 
4.00 
8.00 


0.09 
0.25 
0.40 
0.62 
0.85 
1.20 
1.60 
2.00 
2.60 


0.13 
0.20 
0.30 
0.43 
0.64 
0.84 
1.04 
1.30 
1.60 
3.10 


0.16 
0.24 
0.30 
0.40 
0.50 
0.60 
0.75 
0.85 
1.70 
2.85 
4.30 


0.10 
0.13 
0.15 
0.19 
0.24 
0.30 
0.60 
1.00 
1.50 
2.20 
3.00 
4.00 


0.10 
0.12 
0.15 
0.25 
0.40 
0.60 
0.85 
1.20 
1.50 
2.00 
2.50 
5.50 


0.12 
0.20 
0.28 
0.38 
0.50 
0.65 
0.84 
1.05 
1.25 
2.40 
4.00 


0.09 
0.15 
0.22 
0.30 
0.39 
0.50 
0.62 
1.30 
2.25 


0.10 
0.14 
0.19 
0.25 
0.31 
0.38 
0.82 
1.35 


0.10 
0.14 
0.18 
0.22 
0.45 
0.75 




2,000 




3,000 




4,000 




5,000 




6,000 




7,000 




8,000 




9,000 




10,000 




15,000 




20,000 




25,000 




30,000 




35,000 




40,000 




45,000 


0.09 


50,000 


0.15 


75,000 


0.25 


100,000 


0.40 







Because of the widely different conditions for each installation, 
the proportioning of pipe sizes is determined largely by the judg- 
ment and experience of the designing engineer. It is suggested 



134 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

by the writer that a curve be plotted for each pipe size with 
friction drop in pounds per 100 feet, and square feet of radiation, 
respectively, as ordinate and abscissa. A few ordinates may be 
computed for each pipe size from Table III, due allowance being 
made in 2-pipe work for the decrease in friction resulting from the 
loss of water at each branch connection between the 100-foot 
points, and intermediate values being given directly by the curve- 
Central plant equipment. The equipment of the central plant 
for forced hot-water circulation system of heat consists in general 
of apparatus for reheating and circulating the water, and is the 
same for either type of system. A plant designed for heating 
only is provided with steam boilers to supply high-pressure steam 
to drive the circulating pumps; an exhaust heater in which the 
exhaust steam is condensed, the latent heat being absorbed by 
the circulating water; and water heating boilers to furnish the 
additional heat needed. The water is forced from the pump 
through the heaters, thence through the heating boilers to the 
flow main in the street. 

Where heating is done in conjunction with the generation of 
electricity, the exhaust steam from all units is used to reheat the 
water of the heating system. Where sufficient exhaust steam is 
not available at all times a live-steam heater is installed as a 
booster, and by which the whole system can be taken care of 
temporarily. 

Many plants have been equipped with economizing coils in the 
smoke duct between boilers and stack, but because of a rapid 
decrease in efficiency with length of service, and constant need ol 
repairs, their use has been generally abandoned. 

Co-minglers or injectors in which the exhaust steam and cir- 
culating water are mixed directly, as in an open-pipe feed-water 
heater, are used to some extent, and where they do not intro- 
duce oil into the heating system have proved very efficient. 

The return water is passed through one or more units, carry- 
ing live or exhaust steam or flue gases, either in series or paralleL 
Two or more combinations are provided and serve as a means for 
regulating the temperature of the water. 

Exhaust and live steam heaters. Both types of heaters are 
cylindrical steel shells with heads bolted on, and with l|-mc!i 
charcoal iron, or 1-inch corrugated copper or brass tubes, ex- 



HEATING BY FORCED CIRCULATION 135 

panded into steel plate partitions. Tubes are generally staggered 
and are placed far enough apart to prevent weakening the tube 
sheets. Heaters are placed on end to economize floor space, 
are located close to the circulating pump on the discharge side, 
and are by-passed so that either one or both may be used as con- 
ditions warrant. Steam enters the heaters near the top and sur- 
rounds the tubes, through which the water flows upward, the 
hottest water coming in contact with the hottest steam thus 
insuring the highest temperature of water possible with a given 
quantity of steam. 

With return water at 150° F., a transmission of 6000 B.t.u. per 
square foot per hour with steel tubes and 7000 B.t.u. with cop- 
per or brass tubes is allowed, and the size of exhaust heater de- 
termined accordingly. The heat transmitted by the live steam 
heater will vary with the pressure of the steam, and as a water 
temperature as high as 240° is often desired for abnormal outside 
weather conditions the live steam heater is designed to with- 
stand the full boiler pressure, the tube surface usually being one- 
third to one-half that of the exhaust heater. Standard practice 
in boiler design is followed in determining thickness of shells and 
spacing of rivets. 

Heat available per pound of exhaust steam. The heating 
value of exhaust steam will average 85 per cent of that of satur- 
ated steam at the same pressure or 850 B.t.u. per pound. 

Size of heater connections. Exhaust steam at atmospheric 
pressure occupies a volume of 26 cubic feet per pound, and a 
velocity of 6000 feet per minute is allowed in piping, hence 

pounds steam per minute X 26 . » . , . , 

^wt^k = Area of steam connection to 

6,000 

heater in square feet. 

Each pound of water absorbs 30 B.t.u. in becoming heated from 
150° to 180°, therefore 850 -f- 30 = 28 pounds of water per pound 
of exhaust steam. 

Circulating pumps. Pumps are usually of the centrifugal type 
and operate with an average efficiency of 70 per cent against 
heads up to 125 feet. For small installations, provision for con- 
tinuous operation in case of break-down or necessity for repairs 
is made by installing pumps in duplicate, each of a capacity 



136 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

equal to two-thirds the maximum requirement. In large installa- 
tions pumps capable of circulating 200 cubic feet of water per 
minute, and rated at 75,000 square feet of radiation each, are 
installed in parallel, additional pumps being added as the system 
is extended. 

Pumps are direct-connected to steam turbines or electric motors. 

Expansion tank. An expansion tank, with a capacity of 2 to 
5 per cent of the total volume of water in the system, is installed 
in the power house or in the highest building on the line. A 
closed type of expansion tank is used when the water is circu- 
lated at temperatures over 212°, a pressure of 3 to 5 pounds 
above the static head on the system being maintained from the 
city water-mains through a regulating valve, or by a small elec- 
trically-driven air compressor, which is arranged to start and stop 
automatically. A 2-inch safety valve with waste pipe is also 
provided. Wherever possible the expansion pipe is taken from 
the return main as near the suction side of the pump as possible. 

Water heating boilers. Boiler headers are arranged so one or 
more boilers of the battery may be used to supply additional 
heat to the out-going water, and in many plants the entire heat- 
ing is done by water boilers with electric motors to drive the 
circulating pumps. 

A boiler horsepower equals 34.5 pounds of steam evaporated 
from and at 212° = 34.5 X 970 = 33,465 B.t.u. 

33,465 " 

7Z7-— — — 7 = 180 square feet radiation per boiler horse 

170 + 10 per cent 

power. 

33,464 



30 



= 1115 pounds water to be circulated per boiler horse 



power. 

Gauges and thermometers. Pressure gauges are provided on 
the supply and return to each pump and on the mains where 
leaving the power house. 

Thermometers are placed on the flow and return connections 
to each heating unit, and on the flow and return mains where 
same enter the central plant. 



CHAPTER IV 
PLUMBING, DRAINAGE AND WATER SUPPLY 

Before the acquisition of property upon which a Federal build- 
ing is to be erected, a local engineer is employed to prepare a sur- 
vey of the site and note thereon the size and location of all sewers 
and water and gas mains; also the elevation of the inverts of the 
sewers below or above city datum. 

In order to determine from the survey whether the sewers 
available are sufficiently low to drain plumbing fixtures to be 
located in the basement, the first step is to decide which way the 
building will face, and then find the elevation of the top of the 
street curb midway of the lot; assuming that, as usual, the base- 
ment floor will be established 6 feet 6 inches below that level, 
and that the basement toilet-room will be located in the furthest 
corner of the building from the sewer it is decided to enter. The 
soil pipe in this toilet-room is assumed to be 8 inches to center 
below the basement floor at the start, and a grade of f-inch in 
1 foot fall is assumed for the measured run from the basement 
toilet-room to the sewer. The estimated fall plus the 8 inches 
above noted is subtracted from the assumed basement floor ele- 
vation, and comparison of the result with elevation of the center 
line of the city sewer will show at once whether it is feasible to 
enter the sewer selected, and, if not, whether any of the other 
adjacent sewers may be used. 

If it is found to be impracticable to enter any sewer which will 
serve basement fixtures, the architectural draftsman is so advised, 
and he arranges to place all plumbing fixtures on an upper floor. 

If there are no public sewers the local engineer who prepares the 
survey ascertains and reports whether any sewers owned by pri- 
vate citizens are in the vicinity of the Federal property, and if 
such exist, gives all data in connection therewith and states 
whether permission to connect could be secured. If satisfactory 
service can be obtained at a suitable yearly rental, the building 
wastes are discharged into the private sewer. 

137 



138 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

In the event there is neither a city nor a suitable private sewer, 
the engineer reports whether the government can install its own 
sewer through the city streets to some outfall where nuisance will 
not be created at the point of discharge; and if such a sewer is 
feasible he submits a drawing showing the proposed route and 
profile. 

The government will not build its own sewer unless the city 
will grant an irrevocable license to install and control same. 

In the event no public or private sewers exist, and no feasible 
route or outfall can be secured, the engineer reports whether a 
cesspool would be feasible, and describes the manner of construct- 
ing cesspools in that locality. 

If there are neither city nor private sewers, and on account of a 
clay soil a cesspool is not feasible, the engineer reports whether 
there is near the building a small creek or normally dry ravine 
into which it would be possible to discharge the effluent from a 
septic tank without any filtering. Before resorting to the last 
expedient special permission is always obtained from the local 
authorities, who are advised that the effluent from a septic tank 
is very offensive to eye and nose. 

In a very limited number of cases it is found that there is no 
sewer of any description and that none can be constructed; that a 
cesspool is not feasible, and that no point of discharge can be 
secured for a septic tank. Under these adverse conditions a 
septic tank is installed and the effluent is discharged by gravity 
only (due to the level ground of site) into subsoil drains surrounded 
by gravel laid about 14 inches below the surface of the ground. 

The office is very reluctant to employ either a septic tank or a 
cesspool, and rather than do so will go to heavy expense in install- 
ing a sewer for exclusive use of the Federal building. 

In designing a sewer the following basic data are used : 

Sewer must never be less than 8-inch diameter, and (except one 
length outside of each manhole where it passes under car tracks, 
and at the outfall into a stream or river where the sewer is con- 
structed of extra-heavy cast-iron) it must be of salt-glazed earthen- 
ware pipe, with joints made with an oakum gasket and one-to-one 
Portland cement and sand. Manholes are placed at each change 
in direction, and on straight runs are spaced 300 feet apart. 
Manholes are made 3 feet inside diameter, and 9-inch-thick walls 



! 



PLUMBING, DRAINAGE AND WATER SUPPLY 139 

©f sewer brick are used until manhole is 12 feet deep; and over 
this 13-inch walls are used. The floor of manhole is concrete and 
is made 12 inches thick, with a channel hollowed out in the con- 
crete to connect the inlet and outlet pipes. The floor is made on 
an angle to grade to this open channel. In manholes over 6 feet 
deep iron ladders are installed. All manhole covers are solid, 
and with frame weigh not less than 315 pounds each. 

The earth cover over sewer is never less than 18 inches deep and 
is made at least 3 feet deep if possible. The sewer outfall at 
the stream or river where earth banks exist is protected by a 
dwarf wall of concrete. 

Both sanitary wastes and roof water are conveyed in this sewer 
and a grade of |-inch in 10 feet is desirable, but if conditions de- 
mand 1 inch in 10 feet may be u£ed. A velocity of over 8 feet 
per second is not allowed if it can be avoided without great ex- 
pense for excavation. 

Septic tanks are constructed on the following basic data: 

Tanks are made rectangular and with a depth of liquid of not 
less than 5 feet; and are of sufficient capacity to contain all the 
sewage discharged by the building for a period of 8 hours based 
on 100 gallons per day per occupant, or on 500 gallons per plumb- 
ing fixture per day if number of occupants is not known. 

Tanks are constructed of concrete with walls and bottom 8 
inches thick and with 6-inch-thick reinforced concrete cover with 
manhole. While the present practice commercially permits the 
use of open tanks, covered tanks are demanded by conditions in 
connection with the buildings under discussion. 

Cesspools are generally constructed of hard-burned common 
brick, and are usually 8 feet to 10 feet in diameter and 20 feet 
deep. If there is a sand or gravel stratum, the walls of cesspool 
are run down into same 3 or 4 feet, or far enough to penetrate 
ground water if same exists. Where ground water stands at a 
definite level in the cesspool, as is sometimes the case in western 
Maryland and Pennsylvania, the inlet pipe is turned down below 
the level of ground water to favor septic action. A solid 315- 
pound manhole frame and cover is placed on cesspool and a vent 
pipe is taken from near top of cesspool and run up inside of build- 
ing to above the roof. 



140 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

When cesspools are used an effort is made to have all plumbing 
fixtures located on upper floors, as fixtures in basement will over- 
flow by reason of filling up of cesspool. 

It hardly seems credible that cesspools would be tolerated in 
any civilized community, but a large number of prosperous towns 
still cling to their use. 

For use in cases where a combined system of sewers is provided 
in a city, and also in proportioning a drainage system for roof 
water and sewage or for roof water only, the following table, which 
is sufficiently accurate for all practical purposes, was made some 
years ago by the writer and has ever since been used with success 
by the office. It is based on the very conservative data of sewer 
running full when the rainfall is at the rate of 6 inches per hour, 
and on a speed in sewer of approximately 3 feet per second, the 
minimum speed permissible, and which requires a grade of not 
less than 1 inch in 10 feet for all sizes up to 6 inches. Even in 
the larger sewers the grade is made not less than 1 inch in 10 feet. 
A speed of 8 feet per second should not be exceeded in a strictly 
sanitary sewer, as an intermittent flow, such as these sewers are 
subjected to, will cause the liquid to deposit the solids held in 
suspension. 

Area of roof Diameter of pipe 

Square feet Inches 

1,000 3 

2,000 4 

3,000 5 

4,500 6 

9,000 8 

16,000 10 

25,000 12 

35,000 14 

50,000 16 

75,000 18 

The distance between outlets in roof gutters should not exceed 
60 feet. Three-inch diameter downspouts from main roof may 
be used with safety. 

When a drainage system is proportioned for disposal of sani- 
tary wastes only, the office employs the following data : 



PLUMBING, DRAINAGE AND WATER SUPPLY 



141 



Connection 

Water-closet.... Iiu * n 
4 

Siphon jet slop sink ' a 

Ordinary slop sink and floor drains and stall type urinals . . . . 3 

Kitchen sink 2 

Siphon jet urinal bowl 2 

Shower-bath ' ' 

Bath-tub ' i 

Single lavatory -. \ 

Two to twelve lavatories o 

Ice box floor drain o 

Maximum number of water-closets to connect to various size 
pipes : 

Size of pipe Number of 

a water-closets 

- 12 

\ 24 

o 70 

10 105 

U 355 

Small fixtures in number not exceeding twice the number of 
water-closets given above may discharge into the lines without 
the size being increased. 

_ In the event a separate rainwater disposal system is to be de- 
signed with no sanitary connection or area drain connections near 
basement floor the following tables may be used with safety: 

Area of roof ^^Sf/w P** in inches 

Sauarefeet ™*£*% ^ 

2,200 4 

3,500 5 

5,000 6 

13,500 8 

19,000 9 

31,000 10 

51,000 12 

Area of roof Diameter of pipe in inches 

Square feet with i inch fall 

\ ~~~ Per foot 

2,500 4 

4,500 5 

8,000 6 

18,000 8 

41,000 10 

69,000 12 



142 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

One-quarter of an inch per foot is the standard grade for which 
recessed drainage fittings are pitched, but this can not be obtained 
in fireproof buildings when pipes are run in floor construction, and 
said pipes are run practically level and give good service. 

When a combined system of sewers is in use in a city, it is im- 
portant to protect the fixtures located in the basement of the Fed- 
eral building from overflow which may result from backing up 
of the city sewers. This is accomplished by connecting the drain 
pipe serving the basement fixtures independently to the main 
house drain and installing near the point of junction a back-water 
valve and a hub-end gate valve on the basement toilet-room 
drain. Then if city sewer backs up the basement fixtures may 
be cut off and the roof-water continue to enter city sewer, and the 
fixtures on the upper floors be kept in use. A J-inch diameter 
vent pipe is taken from the back-water valve or near same, and 
connected near ceiling of basement to a vent pipe so as to relieve 
the piping system of air when the back-water valve closes. The 
back-water valves are specified to stand open normally. Base- 
ment window areas are protected with back-water cesspools, or 
back-water traps. 

Under adverse conditions, where city sewers are inadequate 
and overflow constantly, or where the fixtures in basement must 
be located below any city sewer, then the " Shone" or equal type 
of sewage ejector is used, together with a motor-driven air com- 
pressor and air tank for the purpose of automatically discharging 
the low-level sewage into the city sewers. These devices have 
proved most satisfactory in service, with practically no shut- 
downs for repairs. 

Where sanitary sewers exist in a city, or a cesspool or septic 
tank is in use and there are no sewers for the disposal of rain water 
from roof, the roof-water is discharged on the surface of the ground. 
As a general rule, the discharging of roof-water on driveway in 
rear of building is prohibited on account of danger to horses dur- 
ing freezing weather. The down-spouts are nearly always brought 
down on inside of building and discharge on drip stone or a grass 
plot, or enter rectangular cast-iron gutters set in sidewalk with 
covers flush with surface of walk. These cast-iron gutters dis- 
charge into street gutters. 

In all cases where downspouts are collected in the roof space or 



PLUMBING, DRAINAGE AND WATER SUPPLY 143 

in an unheated attic, the pipes exposed in said space are covered 
with 2 inches of hair-felt with a canvas jacket to prevent freezing. 

When the local engineer who prepares the survey reports that 
ground water exists within 8 feet of the surface of the site, the 
practice of the office is to install around the exterior of the build- 
ing an agricultural or subsoil drain consisting of 4-inch-diameter 
salt-glazed earthenware hub sewer pipe laid at a grade of J inch 
to \ inch in 10 feet and surrounded on bottom with a 3-inch bed 
and on both sides with a 6-inch bed of gravel or 2-inch broken 
stone. This stone or gravel fill is carried up to within 1 foot of 
grade and covered with hay or burlap, and then sodded over. 
The summit of the agricultural drain is made not less than 3 
inches below basement floor, and the joints in the pipe are 
cemented on the bottom and half way around to maintain a chan- 
nel. The upper part of the joint is open and covered with a 
layer of burlap. 

The agricultural drains discharge into a brick manhole 3 feet 
diameter with concrete bottom and manhole cover similar to a 
regular city-sewer manhole. The inlet pipe to manhole is pro- 
vided with a cast-iron quarter-bend, turned down to form a 
water seal and prevent sewer air entering the sub-drains. The 
outlet pipe is provided with a back-water valve, and said pipe 
is connected to the building sewer. 

As local and state ordinances do not apply inside the Federal 
lot line, the office is not hampered thereby in the design of plumb- 
ing and drainage systems, but outside the property limits com- 
plies with local regulations, such as those which prohibit discharg- 
ing roof-water into sanitary sewers, or which require the installa- 
tion of a running trap on main house drain. The office is strongly 
opposed to the last-named device, and installs it only under pro- 
test in towns which continue to cling to this antiquated expedient. 

Cases are frequent where only sanitary sewers are in use, and 
it is necessary to drain into same the small basement entrance 
and window areas. Permission to do this is always readily 
granted by the local authorities. 

If a basement entrance or window area is to be connected to 
the drainage system of building under basement floor, a cesspool 
without a bell trap is placed in the area and the pipe connection 
is brought into the building below basement floor and provided 



144 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

with a running trap with clean-out screw flush with basement 
floor. This trap prevents water being held in the cesspool and 
freezing (as with the common cesspool with bell trap), and also 
prevents the escape of drain air at this point when cesspool covers 
are removed. 

If the area cesspools connect to a drainage system located on 
exterior of the building, as may be the case where separate storm- 
water sewers exist, the bell trap is omitted as before noted and 
a "P" trap is used at base of the vertical from the cesspool pipe. 

As early as 1892 the writer urged upon the office the adoption 
of the end-vent or circuit system of plumbing, originated by Wil- 
liam Paul Gerhardt, and also strongly advocated the omission of 
a running trap on the main house drain. The office accepted 
both improvements about 1894 and has used them continuously 
since that time with great success; and its example has undoubt- 
edly had much weight in bringing about a wide adoption of the 
end-vent system and the consequent abandonment of the com- 
plicated back-venting systems. 

In the early days of this advancement the office met with much 
criticism from local inspectors in various small towns where Fed- 
eral buildings were being erected, but protests along this line are 
now so infrequent as to indicate that ancient history has been 
abandoned as a guide in the practice of plumbing. 

In the end-vent system the soil pipes are extended up above 
the roof full size, as are the dead-end vents in most cases, and no 
traps are placed at the foot of the interior downspouts unless they 
open within 20 feet of a window. 

The mains are carried close to the fixtures, and the dead ends 
to fixtures do not as a rule exceed 6 feet in length, which is equiva- 
lent to a developed length of 10 feet. These short dead ends re- 
ceive sufficient oxygen to maintain the bacteria active. 

The omission of the running trap and the generous size and 
number of vent pipes extending above the roof serve to create a 
positive current of air from the city sewer through the plumbing 
system and thus help to ventilate the city sewer, a very desirable 
feature. It is of interest to note that if a cleanout plug is removed 
on one of these systems at the base of a soil or waste stack, a 
strong and continuous current of air from the room into the pipe 
will be observed. 



PLUMBING, DRAINAGE AND WATER SUPPLY 145 

Siphon-jet water-closets and urinals are used exclusively. All 
traps on other fixtures are non-siphoning, except the floor drains 
from shower-bath stalls, which are always end-vented for protec- 
tion against siphonage. 

All soil, waste, vent, and drain piping below basement floor, 
and from building to cesspool, septic tank, or city sewer (if the 
latter is within 200 feet of the building), is extra-heavy cast-iron 
hub-and-spigot pipe with lead-caulked joints, either coated or un- 
coated. The fittings thereon are extra-heavy to correspond to 
pipe. No pipe below basement floor is less than 2-inch diameter. 

Cleanouts are used on horizontal runs below basement floor and 
are located in brick or concrete manholes with iron covers set flush 
with basement floor. These cleanouts are located so that the 
piping system may be rodded to clean obstructions, and they are 
located not over 40 feet apart on straight run,s. 

Brass screw-joi,nted cleanout plugs are located at the base of 
all vertical soil waste, and vent pipes, and at base of all vertical 
downspouts where same are connected to the drainage system 
below the basement floor. Similar cleanouts are used on hori- 
zontal soil and waste pipes in toilet rooms above the basement. 

All soil, waste, and vent piping and all interior downspouts 
above the basement floor are made of standard galvanized wrought 
iron or mild-steel pipe with cast-iron, recessed, screw jointed, 
galvanized drainage fittings. 

All brass pipe on sewer side of traps is iron-pipe size and thick- 
ness, and on fixture side of traps is brass tubing. 

Water-supplying piping exposed in toilet-rooms on face of 
marble work and at fixtures is nickel-plated brass pipe, iron-pipe 
size and thickness ; and all other water piping is standard galvan- 
ized wrought-iron or mild-steel pipe. If demanded by the char- 
acter of city water, brass pipe or lead-lined iron pipe is used. 

All valves are standard weight; 2-inch and smaller are brass, 
and larger are iron body. 

No running threads or long screws are permitted in jointing 
any pipe, and in lieu of same all-brass ground-joint unions, flange 
unions, or right-and-left couplings are used. No provision for 
expansion is made in any piping except hot-water piping over 100 
feet long. 



146 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

UNIFORM PLUMBING SPECIFICATION 

About two years ago the Treasury, War, and Navy Depart- 
ments decided to cooperate in designing a complete line of plumb- 
ing fixtures, and to require their respective contractors to furnish 
fixtures in strict accordance therewith. The result is the gov- 
ernment publication entitled " Specification for Plumbing Fix- 
tures, etc., for the Treasury, War, and Navy Department s," 
which may be obtained from the Superintendent of Documents, 
U. S. Government Printing Office, Washington, D. C, at 35 
cents per copy. 

The board which prepared this specification has produced a 
document remarkable for both scope and accuracy, and has ren- 
dered a substantial service to sanitary engineers and to the manu- 
facturers in this line of business. Engineers and architects who 
have had to hear and weigh the claims and counter-claims of rep- 
resentatives of various plumbing-material houses will undoubtedly 
appreciate the relief which the standardization brings. 

The Treasury Department's representative on the board was 
Mr. H. M. Price, Mechanical Engineer, Office of the Supervising 
Architect. 

The following is a brief description of the line of plumbing fix- 
tures in general use in buildings under control of the Treasury 
Department : 

All fixtures (except wash sinks in boiler room) are required to 
be extra-heavy vitreous earthenware of rugged design. 

Closet bowls are required to weigh not less than 54 pounds in 
any case, and in some cases not less than 75 pounds. 

The closet must be capable of passing the ink test in regard to 
flushing. This test requires that the interior surface of the bowl 
from water line up to flushing rim shall be smeared with ink, and 
that upon flushing closet the water level in the bowl must not 
rise, and it must be clearly demonstrated that the flush is reach- 
ing all parts of the bowl surface above the water line. 

The closet must also be capable of discharging with one tank 
full of water 32 sheets of toilet paper spread out on the floor and 
one end balled up and placed below water line of bowl. The 
same number of sheets (loose) lightly balled up and dropped into 
bowl must also be readily cleared out with one discharge of the 
tank. 



PLUMBING, DRAINAGE AND WATER SUPPLY 147 

Slop sinks are of the siphon-jet type with flushing rim molded 
in the bowl, and are supplied with flushing tank and with com- 
bination hot and cold water faucet. 

Urinals are siphon-jet type so designed as to contain a body of 
water in the bowl. For economy in water consumption, pull 
flush tanks constructed similar to water-closet tanks are used on 
urinals. 

Lavatories are made with overflow molded in the bowl, and 
are provided with the ordinary brass chain and rubber plug. 
Self-closing faucets have not proved entirely satisfactory, and the 
" Fuller" or compression type of faucet is used. 

Bath tubs are cast-iron, enameled inside and painted outside, 
and not less than 5 feet long and 24 inches wide, with roll rim, 
and are provided with combination faucets and non-siphoning trap, 
and with either a standing overflow, or a common overflow and 
a brass chain and rubber plug. 

All fire hose is 2-inch diameter, unlined, woven linen, Under- 
writers' hose, with 75 feet of hose to each outlet. Each length of 
hose has a 12-inch long brass nozzle with f-inch opening and nec- 
essary couplings, and is mounted on a first-class hose rack which 
allows hose to hang in vertical loops. 

The shower-baths have a 5-inch diameter adjustable head, and 
are provided with a mixing valve so designed as to prevent scald- 
ing the bather. Floor drains for showers are cast brass, with re- 
movable bar strainer cover not less than 5-inch diameter. 

All urinal stalls, shower-bath inclosures, and water-closet in- 
closures are light-colored marble, lf-inch thick. 

The floor of toilet-rooms are terrazzo, with marble border 
having a sanitary cove cut in same. Marble wainscot J-inch 
thick is used in all toilet-rooms. Height for main toilet-rooms is 
6 feet, and 4 feet 6 inches for private toilet-rooms. Window and 
door trim in toilet-rooms is marble. 

The minimum size of a private toilet-room in Federal buildings 
is 4 feet 6 inches x 5 feet, which allows for the installation of a 
water-closet and a lavatory if entrance door is properly arranged 
and lookout ladder does not interfere. A larger room is provided 
if possible. 

Toilet-rooms which are intended to contain a bath-tub, water- 
closet, and a lavatory are made 5 feet 6 inches x 8 feet 6 inches, if 



148 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

entrance door can be properly placed. Five feet by 8 feet is con- 
sidered the minimum for first-class work. Water-closet inclos- 
ures for men are generally made 2 feet 9 inches to center and 5 
feet deep. 

Inclosures for women are generally made 3 feet clear inside and 
5 feet deep, and inclosure and entrance door extend to within 6 
inches of the floor lines. Wherever possible, a retiring-room is 
provided for women in connection with their main toilet. 

Main toilet-rooms are made as large as a due regard for economy 
will permit. 

It is a practice to screen toilet-rooms opening off corridors so 
that occupants will not be within view when entrance door to 
toilet-room is opened. All toilet-rooms are provided with win- 
dows in exterior walls in order to obtain light and air. 

In the carriers , toilet-room of a Federal building the minimum 
number of water-closets provided is three; and in this room are 
also installed a slop sink, a shower-bath, and at least one urinal 
and one lavatory. 

The proportioning of fixtures in a Federal building is solely a 
matter of judgment and experience, but as a rule one closet to 
ten persons is allowed in the smaller buildings, and one closet to 
from thirty to forty persons in the large buildings, similar to 
school-house practice. 

The number of urinals never exceeds one-half the number of 
water-closets, and the number of lavatories is reduced to a mini- 
mum, generally nor more than two being provided in a large toilet- 
room. 

A slop sink is provided in connection with or adjacent to the 
first-floor lobby, and also in all main toilet-rooms except those 
assigned to women. Lavatories are provided in each office room if 
the appropriation for the building permits. 

In the Philadelphia post office one general toilet-room contain- 
ing 22 water-closets, 12 urinals, and 15 lavatories was provided 
for from seven hundred to eight hundred employees, and proved 
satisfactory. 

A women's toilet room is always provided in the post-office sec- 
tion of a building, and if building is two stories high or over a 
women's toilet-room is also provided on one of the upper floors, 
in the most inconspicuous place possible. 



PLUMBING, DRAINAGE AND WATER SUPPLY 149 

The following report contains valuable basic data upon the sub- 
ject of proportioning plumbing fixtures to occupants of buildings: 

REPORT OF COMMITTEE ON TOILET REGULATIONS FOR INDUSTRIAL 

PLANTS 

Pursuant to instruction, the committee appointed by the chairman of 
the Sanitary Section of the Boston Society of Civil Engineers to consider 
the regulations for toilet facilities in industrial establishments, has com- 
pleted its study and submitted its recommendations in a report from 
which the following paragraphs are abstracted: 

In every establishment where persons are employed, there shall be pro- 
vided within reasonable access a sufficient number of proper water-closets, 
earth closets or privies, and wherever ten or more persons of both sexes 
are employed together, separate water-closet compartments or toilet rooms 
shall be provided for each sex, and shall be plainly so designated. 

The number of seats shall not be less than one to every twenty-five 
males and one to every twenty-five females, based upon the maximum 
number of persons, of either sex, employed at any one time, except that 
where urinals are provided, the number of seats required may be decreased 
by one for each urinal installed; but the total number of seats, however, 
shall not be less than two-thirds the number required above. 

Water-closets and urinals aaust be readily accessible to the persons us- 
ing them. In no case may a closet be located more than one floor above 
or below or more than 300 feet distant from the regular place of work of the 
person using the same. 

All water-closets which are not ventilated directly to the outside air 
by a window, skylight or other opening shall be entirely enclosed in a 
compartment or toilet room, either by extending the side walls to the ceiling 
or by independently ceiling them over at a minimum height of eight feet. 
This compartment or toilet room shall then be ventilated by either: 

1. An exhaust system; or 

2. A stack to the roof at least six inches in diameter. 

Wherever practicable, these toilets shall be relocated so that they will be 
exposed directly to the outside light and air, in accordance with the re- 
quirements for new, installations. 

Every toilet-room or water-closet compartment shall be so lighted that 
all parts of the room or compartment are easily visible at all times during 
working hours. If daylight is not sufficient for this purpose, artificial 
illumination shall be maintained. 

In all water-closet compartments hereafter constructed, there shall be 
at least 10 square feet of floor space and 80 cubic feet of air space per 
urinal or seat installed. 

All water-closets shall be provided with ample power for flushing. 

All water-closets hereafter installed shall have individual bowls made 
of porcelain or vitreous earthenware; they shall be provided with seats 



150 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

made of wood or other non-heat-absorbing material, which shall be coated 
with varnish or some other waterproof substance. 

All woodwork enclosing the bowl of the closet shall be removed and 
the space within the compartments shall be painted with some light-colored 
non-absorbent paint. 

Hereafter, when more than one water-closet is installed in a toilet 
room, partitions shall be provided between the seats. These may be of 
wood if covered with paint or some other non-absorbent material. They 
shall be not less than six feet high, and, where practicable, shall not ex- 
tend nearer the ceiling or floor than one foot. They shall be at least 28 
inches apart. 

The floor of every water-closet compartment or toilet room hereafter 
installed, and the side walls, to a height of 9 inches, shall be constructed 
of material impervious to moisture, and having a smooth surface. 

The floors of all water-closet compartments and toilet rooms shall be 
kept in good repair, and free from large cracks or holes. 

All water-closet compartments hereafter installed in men's toilet rooms 
shall be provided with doors at least three feet in height and they shall be 
hung 24 inches above the floor. 

All compartments used by females shall be provided with doors at least 
42 inches high and furnished with suitable fasteners. 

The use of the iron trough type of urinal is prohibited, and all urinals 
shall be made of impervious non-corrosive materials, shall be individual, 
and preferably of the wall or vertical slab type. 

Where more than ten males are employed a urinal hall be provided; 
urinals shall be provided in the ratio of one urinal to every forty males, 
based upon the maximum number of persons employed at any one time. 
Two feet of wall urinal shall be considered as an equivalent of one urinal. 

The floors shall be constructed of impervious material to at least 24 
inches distant. 

It is recommended that all water-closet compartments and toilet rooms 
shall be kept heated during the working hours to at least 50°F. 

All toilets and urinals shall be kept clean. Regular and thorough cleans- 
ing shall be practiced. Disinfection alone is not to be relied upon. In 
every establishment there shall be one person who shall have direct charge 
of and be held responsible for the cleanliness of all sanitary appliances 
installed. 

In every establishment where persons are employed there shall be pro- 
vided, within reasonable access, a sufficient number of proper washing 
facilities, and where ten or more males and ten or more females are em- 
ployed together, separate washing facilities shall be provided for each 
sex, and shall be plainly so designated. 

The number of wash bowls, sinks or other appliances shall not be less 
than one to every thirty persons, based upon the maximum number of 
persons using the same at any one time. Twenty inches of sink will be 
considered as an equivalent of one wash bowl. 



PLUMBING, DRAINAGE AND WATER SUPPLY 151 

In special industries or departments where there is undue exposure 
to poisonous substances or liquids, or where the work is especially dirty, 
one may be required for every five persons, and in these cases they shall 
be provided with clean, running hot and cold water. 

The washing facilities provided must be within reasonable access as 
above defined for toilets, and at least one wash bowl, sink or other suit- 
able appliance shall be provided in or adjacent to every toilet room. 

All washing facilities shall be clearly lighted at all times during working 
hours. 

All washing facilities or appliances and the floors in and around the same 
shall be kept clean, and regular and thorough cleansing shall be practiced. 

In laying out chases for the reception of the plumbing piping 
12 inches of solid wall is left at the back of the chase in exterior 
walls and 9 inches in interior walls. 

Minimum depth from plaster line to back of chase : 8 inches for 
5-inch and 6-inch pipes, 6 inches for 3-inch and 4-inch pipes, and 
4 inches for pipes smaller than 3 inches. 

Width of chases: 12 inches for two 4-inch pipes, 8 inches for 
one 4-inch or 5-inch pipe, 8 inches for two 2-inch pipes. No chase 
is made less than 8 inches unless structural conditions demand, 
in which event a 4j-inch chase is made for one 2-inch pipe. 

No chase is placed closer than 9 inches to a beam bearing, nor 
closer than 15 inches to a girder bearing, nor closer than 12 inches 
to any window or other opening. 

Unless architectural reasons prevent, all soil and waste pipes 
are run exposed at ceiling of room below toilet-room. 

All water pipes are run exposed in toilet-rooms, none being 
buried in floor or walls. 

The raising of toilet-room floors to conceal piping is not re- 
sorted to unless the conditions absolutely demand that action. 

WATER SUPPLY 

Most of the cities in which Federal buildings are erected have 
a first-class water-supply system, serving water of a good quality 
and at a pressure sufficient to supply all fixtures provided; and 
the problem of water supply for the building is therefore merely 
the proportioning of piping to supply the fixtures and the fire 
hose. 

When the normal city water pressure is in excess of 50 pounds, 
or where the mains are subjected to high pressure during fires, a 



152 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

pressure-reducing valve is installed in the building to protect the 
plumbing fixtures; and the street washers and fire hose are con- 
nected to the main supply pipe between the street main and the 
pressure-reducing valve. 

In towns where there is no water-supply system, or where the 
water is of poor quality, careful investigation is made for the 
purpose of ascertaining whether it is feasible to sink a deep well 
from which all the water required for the building can be obtained. 
Such wells are usually installed by local contractors, who are re- 
required to guarantee a certain delivery during eight hours con- 
tinuous pumping. 

When there is much sand in the deep-well water, as in Texas 
and on the Pacific coast, the well is operated by an air lift, or the 
deep-well pump discharges into a cistern to allow the sand to de- 
posit. From this cistern the triplex house-pumps take suction, 
and they discharge into riveted steel receivers of not less than 800 
gallons capacity. 

The old style of open-roof or attic storage tank is not used in 
Federal buildings except when conditions absolutely demand, as 
when the city water pressure is low during the day and can not 
supply the fixtures on the top story, but rises during the night 
sufficiently to fill an attic tank. Under these conditions the 
daily city water pressure is utilized to supply all the lower floors, 
and the upper floors are supplied by the tank without the neces- 
sity of pumping. 

The requirements for fire protection for any Federal building 
practically govern the size of the main water-supply pipe, which 
is never made less than 2-inch diameter. For the smaller build- 
ings it is assumed that only one line of fire hose will be in service 
at any one time, and for large buildings that all fire hose on one 
floor will be operated simultaneously. The area of a 2-inch pipe 
is allowed for each fire hose in service, and the main supply pipe 
to the building is made of a discharging capacity equivalent 
to the selected number of 2-inch pipes. 

While the main water-supply pipes are approximated on the 
fire-protection service when the city water pressure is sufficient 
to supply all fixtures in the building, fire-protection requirements 
do not govern when a pumping plant must be installed, as the 
pumping plant is proportioned for the supply of the plumbing 
fixtures onlv. 



PLUMBING, DEAINAGE AND WATER SUPPLY 153 

At some Quarantine Stations pumps and piping are installed 
for fire protection only, and then the following basic data are used 
in proportioning the system: 

Pressure at hydrant, 32 pounds; 90 gallons of water per minute; 
100 feet of 2-inch hose with f-inch nozzle. 

Under the above conditions the nozzle will throw water 50 
feet horizontally and vertically, necessitating the spacing of hy- 
drants 300 feet apart. The buildings at Quarantine Stations are 
seldom more than 40 feet high, and usually there are not enough 
attendants to care for more than one hose stream at a time. The 
piping is proportioned to keep the friction losses within a reason- 
able limit, and 2-inch hose outlets are usually provided. 

Triplex pumps driven by gas engines are used for fire protec- 
tion at Quarancine Stations. The size of gas engine is ascertained 
by multiplying the number of gallons of water per minute by the 
pressure at hydrant plus all friction losses (which are never less 
than 50 per cent of pressure at hydrant), and dividing the result 
by 800. 

Where fire-protection service requirements do not govern, the 
size of main service pipe is based on the assumption that the maxi- 
mum consumption of water will be at the rate of 500 gallons per 
day for each water-closet, urinal, shower-bath, lavatory, sink, 
and wall hydrant. 

A terminal pressure of 8 pounds per square inch should be 
maintained at the highest fixture, and the drop in pressure in main 
service pipe (assumed to be 100 feet long) must not exceed 10 feet 
head. With this loss — 



Size of service 


Velocity in feet per second 


Gallons in 24 hours 


l 

2 




4 


3,000 


5 

8 




4 


5,000 


3 

4 




5 


7,200 


1 




4i 

^*2 


16,000 


H 




4 


28,000 


H 




5 


42,000 


2 




6 


86,000 


2| 




61 


144,000 



The above table is sufficiently accurate for all practical purposes. 

Where the, city water pressure is low, say below 30 pounds per 

square inch, the piping is laid out and the pipe sizes carefully cal- 



154 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

culated with this in view. If a water filter is to be installed it is 
charged with a loss of pressure of five pounds 

Practice has fixed the size of branch water-supply pipes to the 
various fixtures as follows: 

Inches 

Water-closet flush tank ^ 

Urinal flush tank \ 

Slop sink flush tank \ 



Slop and other sinks f 

Shower-baths \ 

Bath-tubs \ 

Lavatories \ 

Street washers f 

3. 
4 



Small heating boilers and hot-water heaters 



The branches to toilet-rooms containing three or a less number 
of fixtures are made f-inch diameter; more than three and not 
more than nine fixtures, 1-inch diameter; more than nine and 
not more than twenty-one fixtures, 1J inch diameter; and for 
from twenty-two to thirty fixtures, lf-inch diameter. 

The proportioning of branch water-supply pipes is a matter of 
experience and judgment, as it is based not only on the number 
of fixtures in the various toilet-rooms and on the group of toilet- 
rooms served by one branch or riser, but also on the number of 
fixtures that will be used simultaneously, a difficult matter to 
determine accurately. 

As previously stated, the branch connections to fixtures are 
fixed by practice, and certain conservative sizes are established 
for branches to toilet-rooms containing various numbers of fix- 
tures. The general practice is to allow, when flush tanks are 
used, that a f-inch diameter pipe will serve any fixture, and in 
calculating the proper size of the branch main to a toilet-room, or 
of a riser to serve a group of toilet-rooms, it is assumed that from 
25 to 50 per cent of the fixtures will be used simultaneously. The 
area of a f-inch pipe is allowed for each fixture so used, and the 
branch is selected from an " Equalization of Pipe Area" table. 

In a toilet-room containing eight fixtures with 50 per cent used 
simultaneously this would give the equivalent of four f-inch pipes, 
or a 1-inch branch. With twelve fixtures the branch would be 
l|-inch and with 50 per cent of the fixtures in use simultaneously 
a 1 f-inch pipe would serve thirty-two fixtures. 



PLUMBING, DRAINAGE AND WATER SUPPLY 



155 



For a very large toilet-room with many fixtures the branch 
pipe should be not less than If inches, and not exceeding 25 per 
cent of the total number of fixtures installed should be considered 
as being used simultaneously. 

For the calculation of branch supply pipes the water consump- 
tion of water-closets is well established. The standard flush tank 
is set 7 feet above the closet, and under ordinary operating condi- 
tions it will discharge twenty gallons of water per minute into the 
soil pipe. The water consumption of urinals, lavatories, etc., is 
taken at one-half that amount. 

The following table may be used in proportioning the piping 
when flushometers are to be used : 





WATER-CLOSETS 




TJRINALS 


WATER 












PRESSURE 


Number of 
Closets 


Size of Main 


Size of Valves 


Number of 
Urinals 


Size of Main 


Size of Valves 


pounds 




inches 


inches 




inches 


inches 


3|-10 


1 


H 


14 


1 




1 




3 


2 




2- 3 


-i i 






6 


2* 




4- 6 


x 2 




15-30 


1- 2 


1* 


U 


1- 2 




3 
4 




3- 8 


2 




3- 8 


1 1 
-■-4 






9-16 


2* 




9-12 


-1 1 

L 2 




31-50 


1- 4 


l* 


H 


1- 3 




3 
4 




5-14 


2 




4-10 


1 1 
A 4 






15-24 


9i 

^2 




11-16 


-1 1 
1 2 





The sizes given above are sufficient to supply all fixtures in a 
toilet-room with cold water, and no additional allowance need be 
made for lavatories, sinks, etc. 

Flushing valves are not used except in the large buildings, nor 
where the normal city water pressure at the highest fixture is less 
than 10 pounds; and generally the limit is made 15 pounds to 
avoid large pipe sizes. 

Water filters are used only where the conditions absolutely de- 
mand them. The specifications for filters to be used where water 
is very muddy require the maximum rate of filtration to be four 
gallons of water per minute per square foot of filter area, and in 
slightly muddy waters to be six gallons per square foot per min- 
ute. Under the conditions noted above, with city water of nor- 



156 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

mal turbidity, during the test the filter must deliver the amount 
of water specified, and at the end of an eight-hour run the filtrate 
must be clear and must not contain free alum or any other coagu- 
lant used. 

During the eight-hour test the filter must not require washing, 
and the drop in pressure of water passing through filter must not 
be greater than five pounds. 

The filter must be easily operated,with as few valves as possible; 
and when reversing the flow to wash the filter the bed must not 
be carried out through the waste pipe. 

The filter bed must be not less than 2 feet 6 inches deep, com- 
posed of clean, sharp, quarried granite or quartz ground to the 
proper fineness. Sea or river sand in the filter is not permitted. 
Two units are always installed, each a complete filter, and so 
fitted that the units may be used singly, in parallel, or in series. 
Filters are not used where the entire water supply of the city is 
filtered. 

In proportioning filters, deep wells, and pumping plants, the 
number of occupants is ascertained for any given building, and 
the water consumption is based on a rate of 100 gallons per day 
per capita. Where the number of occupants cannot be ascer- 
tained with any accuracy, the rate of water consumption is based 
on 500 gallons per day for each plumbing fixture. This rate is 
established to cover the maximum demand on the system. 

In the Philadelphia post office the city water pressure was suf- 
ficient to supply only the fixtures in basement and on first floor. 
The fixtures above first floor, numbering 140, had to be supplied 
by pumps, and on the basis given above this required 50 gallons 
of water per minute. Two triplex pumps, one 3-inch x 4-inch 
and one 4-inch x 4-inch, with a combined capacity of 50 gallons 
per minute, were installed. These discharged into a steel receiv- 
ing tank 60 inches in diameter and 10 feet high, in which was re- 
tained a body of air. These pumps have successfully supplied the 
fixtures for years. 

In the Toledo post office a deep well was installed, with a ca- 
pacity based on the installation of 68 plumbing fixtures to serve 
300 occupants. On the rules previously given this would require 
34,000 gallons a day for fixtures, and 30,000 gallons a day in the 
per capita basis. A mean of the above would require approxi- 
mately 22 gallons per minute. 



I 



PLUMBING, DRAINAGE AND WATER SUPPLY 157 

The well is 8-inch diameter and 502 feet deep, and on test de- 
livered 25.8 gallons of water per minute. Before pumping, the 
water in the well stod 128 feet below the surface of the ground, and 
after pumping eight hours at the rate above noted it fell to 168 
feet, rising again when pumping ceased. 

A pump 3f-inch diameter by 24-inch stroke was installed, which 
at 25 revolutions per minute delivers twenty gallons of water per 
minute into a tank against 30 pounds pressure. The pump was 
operated by a deep-well pump head driven by a 5-H.P. motor. 
A 3-inch cylinder with 4-inch-stroke air compressor was installed, 
driven by a 3-H.P. motor, and discharged into a galvanized-steel 
air storage tank with a connection to the air space of the main 
pressure tank. 

The air tank was 18-inch diameter and 5 feet long, with ^-inch 
shell and J-inch heads, and the compresson tank was 60-inch di- 
ameter, 26 feet long and constructed with -^-inch shell and ■£$- 
inch dished heads. Rivets were f-inch diameter, spaced 2| inches 
center to center. Tank was tested to 100 pounds. 

The gauge glass was 24 inches long, and the tank was provided 
with a 11-inch x 14-inch manhole located below the water line. 

The calculation of the horse-power on the usual basis shows 
that with deep-well pumps considerable allowance must be made 
in motor for the weight of the suction rods in spite of the buoy- 
ancy of the water. 

Thirty pounds in tank plus 168-foot lift equals approximately 

110 pounds. 

20 X 110 

— — = 1.3 actual norse-power. 

Taking the pipe friction at 50 per cent of the 110 pounds would 
require 

20 X 170 



1700 



= 2 horse-power. 



Allowing 50 per cent efficiency on working head and 80 per 
cent on motor, the combined efficiency would be 40 per cent, and 
the motor horse-power would be 2 divided by 0.4, which equals 
5 horse-power. 

In Western cities where the water is strongly alkaline it is the 
practice to install a rain-water storage cistern in the basement, 



158 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

and by means of a water-lift or pump elevate this water into a 
storage tank in attic, thence supplying the water for lavatories 
and slop sinks, and for drinking purposes, the flushing of sanitary 
fixtures and sprinkling of lawns being done with city water. 

An excellent example of an installation of this character is in 
the Federal building at Mitchell, South Dakota. The city water 
pressure was over 60 pounds, which made a water-lift preferable 
when relative cost of city water and of electricity was considered. 
The roof area discharging into storage cistern in basement is 
3600 square feet. 

The cistern is 15 feet x 18 feet inside dimensions, divided into 
two compartments by means of a 9-inch brick wall with openings 
at floor of cistern. On the floor of cistern and 12 inches on each 
side of the division wall, 4j-inch-thick brick walls are erected to 
a height of 16. inches, and the space between these walls is filled 
with a layer of charcoal 12 inches deep and covered with a 4-inch 
bed of sand. The filtered-water compartment from which the 
water-lift takes suction is 4 feet 5 inches wide and 15 feet long. 
The downspouts discharge into the large compartment. 

The cistern was constructed on top of the 5-inch-thick concrete 
basement floor, and the bottom of cistern was constructed of a 
layer of water-proofing, 5 inches of concrete, and 1-inch cement 
mortar finish coat. 

The distance from basement floor to top of side walls of cistern 
is 6 feet, and the side walls are 4-inch-thick brick walls plastered 
with 1-inch cement coating, then a layer of waterproofing, and 
then a brick wall with a batter on the exterior, thickness at top 
24 inches and at bottom 36 inches. The entire cistern is covered 
with 2-inch x 8-inch wood joists, 1 foot 10 inches on centers, the 
joists being covered with lj-inch tongued and grooved boards. 
Hinged trap doors 24-inch x 36-inch are placed for access to stor- 
age portion and filtered-water space. Minimum space between 
bottom of first-floor construction and top of cistern is 2 feet 6 
inches. 

The water-lift has a capacity of 600 gallons of water per hour 
and is of the reciprocating type, 3-inch power cylinder by 3-inch 
pump cylinder with a 4-inch stroke, and delivers the water into 
the attic tank with 60 pounds city pressure. The pump governor 
is so designed that the admission of city water is regulated by the 



PLUMBING, DRAINAGE AND WATER SUPPLY 159 

pressure in the lift discharging pipe to attic tank, and when the 
pump is stopped the valve closes and pump is not under pressure. 
The pump has a lj-inch city water connection and a lj-inch 
discharge to attic tank. 

The attic tank is 3 feet 3 inches x 6 feet 6 inches x 2 feet 3 inches 
deep, constructed of J-inch tank steel with 2j-inch x 2|-inch corner 
angles, and is provided with a drip pan 6 inches larger all around 
than the tank. The tank rests in the pan on three 6-inch I-beams, 
and the pan is supported on three 8-inch I-beams. The tank is 
provided with a f-inch tongue and grooved cover, and inlet to 
tank is provided with a ball cock. 

Where space permits, the attic storage tanks usually hold about 
1000 gallons, and for the average Federal building the cistern in 
basement should have a capacity of not less than 10,000 gallons. 

The size of the storage cistern is generally based on containing 
one month's rainfall, assuming the rainfall to be 48 inches per 
year or 4 inches per month. At this rate each square foot of roof 
would catch about 2 \ gallons of water, and in the example just 
given the cistern would be 9000 gallons capacity. 

The minimum size of cistern is based on containing one month's 
storage at rate of 2 inches of rainfall per month. 

If the quality of city water is satisfactory, but an attic storage 
tank is necessary on account of the city pressure being low during 
the day and increasing sufficiently at night to fill the tank, a 1000- 
gallon tank (which will generally be 4 feet x 6 feet x 4 feet deep) 
is installed, and is provided with a drip pan 6 inches larger all 
around than the tank. The tank and pan always have an over- 
flow to basement sink. 

Tank and pan should be constructed of J-inch tank steel, and 
the tank should have one longitudinal and two transverse braces 
lj-inch diameter, set 30 inches above bottom of tank. 

Hot water is supplied to each shower-bath, lavatory, and sink 
in a Federal building. 

The hot-water branch supply connections to fixtures are the 
same as the cold-water connections previously described. The 
hot-water supply pipes to toilet-rooms containing three or a less 
number of fixtures requiring hot water are f-inch diameter. 
When there are more than 3 and not more than 8 fixtures a 1-incb 
diameter connection is made. 



160 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Except in one-story buildings, J-inch diameter return circu- 
lating pipes are taken from each riser near the top and collected 
into a f-inch return main in basement. The return main is con- 
nected with the storage tank and provided with a check valve. 

Where the cost of gas does not exceed 30 cents per 1000 cubic 
feet, a storage-type, automatic gas water heater is installed; other- 
wise a cast-iron coal-burning heater is used. 

In estimating on storage tanks and hot-water heaters for Fed- 
eral buildings twenty gallons in the storage tank is allowed for 
each shower-bath, ten gallons for each sink, and five gallons for 
each lavatory. In the average one-story and small two-story 
buildings this will require about sixty-five gallons water storage, 
or a tank 18-inch diameter by 5 feet long, containing a steam coil 
made of 15 linear feet of lj-inch copper tubing. 

The gas water heater to be supplied with the above-described 
tank must be capable of heating 50° 4 gallons of water per 
minute. Under ordinary conditions this would heat 50° 200 gal- 
lons of water per hour. 

The cast-iron water heater to be supplied with above-described 
tank has a 12-inch diameter grate and will heat 48 gallons of water 
per hour from 40° to 140° F., and at this rate will require firing 
every eight hours. 

The next size storage tank used in Federal buildings is 24-inch 
diameter and 7 feet long, containing 164 gallons of water and a 
steam coil with 25 lineal feet of lj-inch No. 16 copper tubing. 
This tank will serve two shower-baths, five sinks, and from fifteen 
to twenty lavatories, and may be used with the gas heater above 
noted. 

The coal water heater for the above-described tank has a 15- 
inch-diameter grate, and a capacity to heat 96 gallons of water 
from 40° to 140°F. per hour when fired every eight hours. 

The largest buildings have a storage tank 36-inch diameter by 
8 feet long, containing 424 gallons of water and a steam coil con- 
taining 36 lineal feet of 2-inch O.D. No. 16 copper tubing. A 
gas water heated used with this combination should have a ca- 
pacity of heating six gallons of water per minute 50° F.; and a 
cast-iron water heater should have a grate 18-inch diameter, and 
be rated to heat 220 gallons of water from 40° to 140° F. per hour 
when fired once in six hours. 



PLUMBING, DRAINAGE AND WATER SUPPLY 161 

In general, the storage capacity should be determined by the 
foregoing rules; and in the large outfits the cast-iron heater should 
be designed to heat the amount of water in storage tank in two 
hours when the boiler is fired once in six hours. 

DRINKING WATER SUPPLY 

In the smaller buildings used exclusively for post office pur- 
poses, with perhaps a second or third floor containing offices 
little used or of minor importance, and a post office work room 
space of about 2000 square feet or less one drinking fountain is 
placed in the work room and an ice box in the basement. 

In some of the smaller buildings in which the basement is too 
low for sewerage facilities in lieu of the drinking fountain and 
ice box a sanitary water-cooler is placed in the post office work 
room. 

If the work room exceeds about 2000 square feet area two or 
more drinking fountains are placed in it, and if the building con- 
tains a court room a drinking fountain is placed in the corridor 
on that floor, which is generally the second. 

The drinking fountains are of a type hereafter described. The 
wall type are generally used in both work rooms and court room 
corridors, except in cases where there are a number of fountains 
in the work room when only those adjacent the offices and in por- 
tions of the rooms where women may be employed are made wall 
type and the others in the work rooms are made pedestal type. 

The ice boxes are made 48 inches long by 18 inches wide by 33 
inches deep inside. They are lined with galvanized iron and 
have a heavy rack inches above the bottom on which a 400-pound 
cake of ice may be placed. 

Below this rack is a coil of J-inch block tin pipe. This coil 
contains 50 lineal feet of pipe if one fountain is used, and 100 
lineal feet if two fountains are connected to it. 

The boxes have a valved drain out of the bottom and an over- 
flow 6 inches above the rack which holds the ice. Thus the coil 
is always submerged. 

The box is made of f-inch tongue and grooved hard pine inside 
and outside and on the bottom and sides is insulated with 2 
inches of granulated cork or cork board between the exterior and 



162 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

interior wood linings. The cover is made of double thickness, 
f-inch tongue and grooved hard pine with 2 inches cork between 
and is hinged and counterweighted. 

The coil is connected to the water supply system on the inlet 
side and the outlet side runs as direct as possible to the fountains. 
Generally a pressure reducing valve is connected in the supply 
line to the ice box as the pressure at the fountain must be nicely 
regulated. 

The lines from ice box to fountains are insulated with cork cov- 
ering same as hereafter described for the ice water lines of the 
larger installations. 

The sanitary water coolers sometimes used in the work room 
have a water chamber or coil which is connected to the water sup- 
ply system of the building and a bubbling cup is attached to the 
outlet. This bubbling cup wastes into a chamber underneath into 
which the melted ice wastes and this chamber is connected to the 
sewer system through a trap. 

No attempt is made to circulate the lines between the ice boxes 
and the fountains and the runs are made as direct as possible. 

When more than two fountains are required a system of me- 
chanical refrigeration is installed. 

In such cases consideration is given to the plan of confining 
the drinking fountains to the post office work rooms, the court 
room corridors and other semi-public places and making ice water 
connections to the lavatories in the office rooms and in the private 
toilet rooms. 

The alternate plan to this is to install wall type fountains in 
the corridors on the various floors in lieu of lavatory faucets. 

If funds are sufficient to place lavatories in the office rooms, 
and if the rooms are used enough and of sufficient importance, 
the former plan is favored. 

When funds are limited, and in old buildings where the cutting 
and patching item for a large number of faucets would be large, 
the latter plan is resorted to but not favored. 

There follows a description of the systems of ice water supply 
in which the water is cooled by mechanical refrigeration. 



I 



PLUMBING, DRAINAGE AND WATER SUPPLY 163 

REFRIGERATION 

The refrigeration plants designed and installed by this office 
are generally small plants for cooling the drinking water for the 
occupants of the building. 

In large buildings where there are many water coolers to be 
iced each day and kept clean, thus entailing considerable expense 
for ice and a large amount of janitor service, such plants are a 
positive economic gain; to say nothing of increased convenience to 
the occupants. 

Such plants generally consist of a compressor, generally motor 
driven; a condenser, generally of double pipe reverse current 
type ; a cooling tank in which a refrigerant coil is immersed and an 
ice water circulating pump, generally a motor driven triplex 
pump; in the basement. A system of ice water supply pipes are 
run at the basement ceiling connecting with supply risers passing 
up through the building and to the attic where they are collected 
together in a system of piping similar to that at the basement 
ceiling and run and connected into the bottom of a tank called a 
balancing tank. 

From the side of this balancing tank near the top an overflow 
pipe is connected and carried down to the basement and dis- 
charged into the cooling tank through a perforated pipe extending 
around the circumference of the tank just above the water line. 

Systems. The specifications permit either the ammonia, car- 
bon dioxide or ethyl-chloride systems to be used without any 
preference for any particular one. The contractors so far have 
generally installed the ammonia systems. 

Compression systems are specified, and in the ammonia systems, 
both the compact self contained outfits, and the ordinary outfits 
in which each part of the apparatus is a separate piece of equip- 
ment, are permitted. 

In certain cases such as hospitals the ammonia type of ma- 
chines are not used. 

Compressors. Except in a few cases, where unusually large 
machines are used, the compressors are required to be vertical, 
single acting, single or double cylinder, of the enclosed crank case 
variety. No stuffing boxes are permitted except on the crank 
shaft. Such machines are required to be splash oiling and have 



164 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

an oil gauge and an oil pump is supplied and attached to the ma- 
chine. The covers of the crank case are required to be ground 
to a perfect fit without any gasket being used. 

Rotary compressors are permitted if ethyl-chloride is to be 
used as a refrigerating medium because the pressures are low. 
The difference in pressure between the high and low is only about 
25 pounds under ordinary conditions while the pressure difference 
for ammonia is 150 to 175 pounds and for carbon dioxide very 
much more than for ammonia; generally about 800 pounds per 
square inch. 

The usual structural features of machines are embodied in the 
specification, which does not attempt to give the cylinder dis- 
placement, size, etc., leaving that for the manufacturer. 

The machines are specified to be of a capacity sufficient to 
abstract a stated number of B.t.u. per hour from the water in the 
cooling tank when the tank is supplied with water at 75° and 
cooled water drawn off at about 40°. All losses in the plant up 
to this stage are charged against the compressor. 

Compressors are generally belt driven but often space requires 
them to be chain driven from the motor, in the latter both being 
mounted on a cast iron bed plate. 

No outfits of less than two tons refrigerating capacity (22,000 
B.t.u. per hour), at the cooling tank are used. It is good policy 
to use machines of ample capacity and large cooling tanks for 
storage purposes. In this way the machine can run a few hours 
a day, when some one can take care of it and the circulating 
pump can be safely intrusted to run constantly without unusual 
attention. 

The machines are not required to be automatic; that is, to have 
an automatic method of starting and stopping to keep the water 
in the cooing tank at a predetermined temperature. 

Condensers, separators, etc. The refrigerant condensers are 
placed in the basement near the compressor, and except for the 
self contained types of machines, are the double pipe reverse 
flow type. 

They are made of lj-inch and 2-inch extra heavy pipe with 
special extra heavy return bend fittings. 

Water supply and waste connections are provided to take care 
of 3 gallons per minute per ton of rated refrigeration capacity. 



PLUMBING, DRAINAGE AND WATER SUPPLY 165 

The lineal feet of pipe required for these condensers is given in 
a table hereafter. 

Oil separators, liquid receivers, etc., are required to be of ample 
size and properly connected in the usual manner. 

A gauge board is mounted in some central location on which are 
placed gauges for the high and low side of the compressor and for 
the water pressure at the circulating pump discharge. 

Cooling tanks. The cooling tanks are made liberal in size to 
provide storage capacity. They are cylindrical, open top and 
made generally of 3^-inch galvanized sheet steel riveted and all 
edges tinned and soldered. 

The table given hereafter gives the size of cooling tanks used 
for different size machines. 

The tanks are set on double layers of 2-inch thick cork board 
laid in asphalt, which in turn stands on a concrete foundation 4 
inches above the floor. The sides of the tank are lagged with 
tongue and grooved hard pine or hardwood filled and varnished. 
The 8-inch space between the tank and this lagging is packed 
with pure granulated cork. The top consists of double 1-inch 
hard pine or hardwood boards between which is placed 1-inch 
thick cork board. The top is made in two halves and remov- 
able. All pipes entering the tank, except the flow and return 
for refrigerant which enter through the cover, are entered through 
the sides of the tank and flanges are provided for that purpose. 

Tanks are provided with a water supply, generally f inch con- 
trolled by a float valve set to keep water line 6 inches below top 
of tank; a drain out of or near bottom provided with a valve and 
an overflow out of side near top, discharging over a cesspool 
which is connected with the sewer system; and a connection 
near top for the return of the circulated water from the balancing 
tank in the attic. The suction of the circulating pump is taken 
from the side near bottom of this tank. 

A brass case thermometer is fitted in the suction pipe to the 
circulating pump and a similar one in the return pipe from the 
balancing tank. 

Cooling coils. The cooling coil is generally a spiral coil of 2- 
inch extra heavy pipe galvanized on outside with welded joints. 
On the inlet of this coil outside the tank an expansion valve of 
the needle type is placed and the outlet of this coil is connected 



166 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

directly to the compressor suction. The top of this coil is placed 
6 inches below the water line maintained by the float valve and 
overflow. The number of feet of pipe in the cooling coil for the 
various size plants is given in the table herafter. 

Circulating pump. The circulating pump is placed as close as 
possible to the cooling tank in which its suction is connected and 
the discharge runs to the various rising lines which supply drink- 
ing water to the various fountains and faucets throughout the 
building. These pumps are generally motor driven triplex 
pumps with a silent chain drive, motor and pump being mounted 
on one cast-iron sub-base. 

The pumps are designed of proper capacity to circulate sufficient 
amount of water in order that the return water to the cooling 
tank will be about 5° warmer than the water leaving the tank 
which is generally five to ten times the amount of water consumed 
for drinking purposes. 

The method of determining this will be given hereafter. 

These pumps and motors are often placed in duplicate, and this 
is the only part of the apparatus which it is deemed necessary in 
any case to duplicate being the only machine which is presumed 
to be in operation all the time. 

By pass arrangements. In cold climate it will often be found 
that if a by pass arrangement is made to by pass the cooling 
tank and circulating pump, so that all or part of the water used 
for general purposes is first passed through the circulating pipes 
of the drinking water system and thence into the general water 
supply piping of the building, the refrigerating plant will have to 
run very little during the winter months. The high non-con- 
ducting qualities of the covering on the drinking water lines often 
is sufficient to prevent the absorption of much heat until the 
water has passed through the drinking water system, whereas 
often in case of large buildings the water drawn from the lava- 
tory faucets would be too warm for this purpose. 

Balancing tank. The balancing tank is placed in the attic and 
is provided with a tap in the bottom to which the horizontal 
mains from the top of all rising lines are connected and a tap near 
the top from which a line is run down to the cooling tank in the 
basement. 

This tank is generally a closed range boiler and is covered with 



PLUMBING, DRAINAGE AND WATER SUPPLY 167 

a double thickness of 2-inch moulded cork jacket covered with 
canvas. It is provided with a hand hole and cover. 

The size of the balancing tank will be given in a table here- 
inafter. 

It will be seen that this tank provides a free egress for all air 
in the circulating lines and a small water storage in case of short 
shut down of the circulating pump in the basement. 

Circulating lines. The circulating lines are started from the 
pump discharge and lead to the base of all rising lines which pass 
upward through the building, being offset as required to reach the 
various fountains and faucets. In the attic the tops of these lines 
are connected together and run to the balancing tank. 

The ice water lines are galvanized wrought iron or mild steel, 
unless the character of the water requires some other kind, and 
the fittings are cast or malleable, galvanized. 

The rising lines are generally made J-inch diameter. Propor- 
tioning the mains is done by adding the sizes of the various rising 
lines together according to the following table: 

§-inch = 1 l^-inch = 15 

|-inch = 2 2 -inch = 30 

1 -inch= 5 2|-inch = 55 

l£-inch = 10 3 -inch = 85 

Thus a line to supply 10 J-inch rising lines would be lj-inch 
and after 5 rising lines had been taken off the main is reduced to 
1-inch, etc. 

The mains in the attic to the equalizing tank are proportioned 
in the same manner. 

The dead end immediate connections to the fountains and 
faucets are made f-inch and generally are iron pipe size brass 
pipe. 

All lines must of course grade upward from pump to balancing 
tank to prevent air pockets. The overflow line from this tank 
must run without traps so that the balancing tank can be re- 
lieved of air through this line. The overflow line is 1J inches 
for the smaller systems and 2 inches for the larger ones. 

Coverings. This is an especially important item in drinking 
water systems. On an average the refrigeration required to off- 
set the heat losses from pipes, tanks, etc., with even the best prac- 



168 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

tice in covering is just about equal to refrigeration required to 
cool the actual amount of water consumed. In other words the 
best insulation is only 50 per cent " efficient." 

All the ice water pipes, valves and fittings are covered with 
moulded pure granulated cork covering, the commercial thick- 
ness of which varies from 1J to lj inches, depending on the size 
of the pipe. This covering has a mineral rubber lining to resist 
moisture, special precautions are taken to make the covering con- 
tinuous through floors, walls, etc., and the hanger bands are 
placed outside the covering. The covering is applied in halves 
with joints broken and joints made with a mineral rubber cement. 
It is jacketed with canvas, pointed to suit and supplied with 
brass bands. 

The low pressure refrigerant lines, if they are of considerable 
length, and ice water lines in hot locations as in boiler rooms, 
tunnels, etc., are covered with similar covering of the next heavier 
commercial cork covering, known as " brine covering," similarly 
applied. 

Drinking water fountains and faucets. In work rooms, public 
lobbies or toilet rooms ; adjacent to court rooms, and in like places 
where there are a large number of people to drink water from the 
same fixture, vitreous earthenware bubbling cup drinking foun- 
tains are installed. 

One or two standard types are used, depending on whether or 
not in the designer's judgment any one would draw water in a 
glass or pitcher, or whether it is desired to use only the bubbling 
cup. 

One designed to be mounted on the wall has a bubbling cup in 
the bowl and on the back above the bowl is a faucet to fill a glass 
or pitcher. Both the faucet and the cock controlling the bubbling 
cup are self closing. 

The other type is a pedestal type and has only a bubbling cup 
operated by a foot valve and may be set up at any place in the 
room. In the wall type the supply connection is made from the 
wall and in the pedestal type the supply connection is made from 
the ceiling below. 

These two types are known among the fixture manufacturers as 
" Wall type" and " Pedestal type" fountains, Miscellaneous Draw- 
ing No. 308, Supervising Architect's office. 



PLUMBING, DRAINAGE AND WATER SUPPLY 169 

In the larger buildings each lavatory in office rooms is provided 
with a J-inch self closing faucet. In place of the usual hot and 
cold water faucets on opposite sides of the bowl, a hot and cold 
combination faucet is placed on the right hand faucet location 
and the ice water faucet is placed on the left hand end with a 
tumbler holder mounted on the vitreous back. When offices 
have a private toilet room the lavatory is placed in the toilet room 
and none in the office proper. 

In such cases there is a marble w r ainscot generally and the lava- 
tory is without back, in which case the tumbler holder is mounted 
on the marble wainscot above the lavatory. If the toilet room 
had no marble wainscot the lavatory with a vitreous back same as 
in the office rooms would be used. This combination is also shown 
on Miscellaneous Drawing No. 308, Supervising Architect's office 
and as such is known to the fixture manufacturers. 

Methods of calculation. Following is the basic data used in 
designing the component parts of such an ice water cooling plant 
as has been described. 

First locate the lavatory ice water faucets, drinking foun- 
tains, machinery, etc., and lay out the pipe lines according to the 
data given above as to their sizes, etc. Scale up the lengths of 
the different size pipe in the circulating system and compute the 
B.t.u. absorption per 24 hours from the following table; assum- 
ing the standard ice water thickness of moulded cork is to be 
used. This table gives the heat transfer in B.t.u. per 24. hours 
per lineal foot of pipe per degree difference of temperature between 
average water and air. 

f-inch pipe 3.50 l§-inch pipe 5.26 

^-inch pipe 3.84 2 -inch pipe 5.88 

f-inch pipe 4.00 2^-inch pipe 6.98 

1 -inch pipe 4.26 3 -inch pipe 7.30 

1 J-inch pipe 4.78 

The temperature of water is generally taken as 40° F. and the 
air temperature is taken as about the maximum likely to be 
encountered, depending on locality, say about 90° F., on an 
average. 

To this result add 10 per cent to 15 per cent to take care of 
uncovered fixture connections, tanks, pump cylinders, etc., and 



170 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



you have the B.t.u. per 24 hours required to offset the radiation 
losses. 

To get the B.t.u. required to cool the water actually consumed, 
allow \ pint per hour for each occupant who would draw water 
from a faucet in his own room and 1 pint per hour for each occu- 
pant who would use the bubbling fountains. 

Figure on cooling this amount of water from highest probable 
water temperature, usually about 75°, down to 35°. 

The sum of these two items is the maximum required duty of 
the machine and for this duty all parts of the apparatus are 
designed. 

In the following table, the basis of which is the B.t.u. loss per 
hour as ascertained by the above data, are given the dimensions 
of the principal component parts of the apparatus. 

It will be noted that the rated tonnage of the apparatus is 
somewhat in excess of the B.t.u. available for cooling, this excess 
being in greater proportion for small plants than for larger ones. 
This is to cover various losses between compressor and tank, 
possible freezing of some ice on coils, etc. 

The figures for liquid receiver, oil separator, cooling coil, horse- 
power, and condenser are for ammonia plants. For other sys- 
tems such data must be given by the manufacturer to the 
contractors. 



B.T.U. per hour 

Rated tonnage 

B.T.U. per hour for rated tonnage. 

Lineal feet pipe in condenser 

T . . , . f Diameter, in. .. . 

Liquid receiver < T ,, . 

[Length, in 

~., , f Diameter, in 

Oil separator < T , . . 

[Length, in 

-. ,. , [Diameter, in 

Cooling tank < TT . , , . 

[Height, in.. 

Cooling coil, lineal feet 2-inch pipe 

Equalizing tank /Diameter, in 

\ Length, in 

Motor horse-power for compressor 



4,700 


10,600 


22,000 


45,000 


68,500 


i 

2 


1 


2 


4 


6 


5,933 


11,866 


23,732 


47,464 


71,196 


20 


30 


60 


114 


152 


6 


6 


8 


10 


10 


36 


48 


48 


48 


60 


3 


4 


6 


6 


6 


30 


36 


36 


42 


48 


36 


36 


42 


48 


54 


36 


60 


72 


72 


72 


25 


50 


100 


200 


300 


18 


18 


18 


18 


18 


36 


36 


36 


36 


36 


2 


3 


5 


71 

' 2 


15 



92,000 

8 

94,928 

190 

12 

60 

6 

54 

60 

72 

400 

18 

36 

15 



To ascertain the amount of water to be circulated by the pump 
divide the radiation losses per hour by 5 which gives the amount 



PLUMBING, DRAINAGE AND WATER SUPPLY 171 

of water in pounds per hour to maintain a loss of 5° in the piping 
system from pump discharge to cooling tank return. To this add 
the actual amount of water used for drinking purposes bearing in 
mind that this allowance of | gallon and 1 gallon respectively 
per day is for an 8-hour day. This is the amount of water to be 
circulated per hour. 

Example. The following are the actual figures used in esti- 
mating a plant in one of the larger buildings. The calculations 
will give the method of applying the data given above. This 
plant has been in service some time and has given good results. 

There are 8 bubbling cup drinking fountains and 26 lavatories 
with ice water faucet attached. The maximum number of occu- 
pants in the building at one time is 366 for an 8-hour period; as 
over 75 per cent of them will use bubbling fountains exclusively 
figure on 1 gallon per occupant. 

Maximum quantity of water consumed = 366 gallons per 8 
hours = 1100 gallons per 24 hour day. 1100 times 8 J equal 
9166 pounds per 24 hours. 

To reduce this from 75° to 35° requires 9166 times 40 equals 
366,640 B.t.u. per 24 hours. 

The circulating line contains 1115 feet of J-inch pipe; 730 feet 
f-inch; 155 feet 1-inch; 105 feet lj-incli; and 95 feet 2-inch. 
Using the factors hereinbefore given the heat absorption of 
these lines is as follows: 

1115 feet 3.84 = 4260 B.t.u. per 24 hours. 

730 feet 4.00 = 2920 B.t.u. per 24 hours. 

155 feet 4.26= 660 B.t.u. per 24 hours. 

105 feet 4.78= 500 B.t.u. per 24 hours. 

95 feet 5.88= 560 B.t.u. per 24 hours. 

Total =8900 B.t.u. per 24 hours per degree differ- 
ence between water and air. 

Take room temperature at 90° and water at 40° giving a differ- 
ence of 50°. 8900 X 50 = 445,000 B.t.u. per 24 hours, lost by 
radiation. Adding that required to cool the water gives 445,000 
+ 366,640 = 811,640 B.t.u. per 24 hours, divided by 24 equals 
33,850 B.t.u. per hour. Adding 10 per cent for uncovered fix- 
ture connections, and tanks we have 33,850 plus 3,385 equals 
37,235 B.t.u. per hour as maximum load. 



172 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Referring to first column of table above it is found that the 
nearest larger size standard machine is for 45,000 B.t.u. per hour 
having a rated capacity of 4 tons refrigeration. 

All the various parts of the apparatus were made the sizes called 
for in this table for this size machine. 

Amount of water circulated. Total radiation losses equal 
445,000 plus 10 per cent equals 489,500 B.t.u. 24 hours equal 
20,400 B.t.u. per hour. 20,400 divided by 5 equals 4,080 pounds 
water per hour. 4,080 divided by 8J equals 490 gallons per hour 
to which must be added the water consumed for drinking pur- 
poses which equal 46 gallons per hour. 490 plus 46 equals 536. 
The pump was specified to pump 10 gallons per minute against 
a head estimated at 60 feet, which is the height of balancing tank 
above pump plus the estimated pipe friction. 

The above plant has been tested, placed in service and has given 
good results. 

ESTIMATING 

The following data are used in making preliminary estimates of 
cost of drinking water systems and for checking bids. 

Used with proper judgment as to local conditions they will 
give good results. The figures are based on conditions as they 
apply in cities and larger towns where good labor and material 
are easily obtainable. 

The figures in each case are the contractor's cost for work in 
new buildings and 15 per cent to 25 per cent should be added to 
estimate for contractor's profits. 

Pedestal type drinking fountains in place with non-siphoning 
trap, etc., equal $50. 

Wall type drinking fountain in place with faucets, cocks, and 
fittings equals $60. 

For each lavatory equipped with ice water faucet and combina- 
tion faucet add to cost of lavatory with separate hot and cold 
faucets $5. 

Ice box in basement in place with overflow, cesspool and coun- 
terweight equals $135 with 50 feet of pipe, and $160 if 100 feet 
of pipe is used. 

Sanitary water coolers in place complete with trap and imme- 
diate water supply and sewerage connections, $60. 



PLUMBING, DRAINAGE AND WATER SUPPLY 173 

Refrigerating machines in place including compressor, motor, 
controller, foundations, oil separator, liquid receiver, condenser, 
expansion coils, cooling tank, equalizing tank; all refrigerant 
piping and fittings, water supply and waste to condenser and 
compressor jacket, triplex circulating pump and motor, all com- 
plete per ton of rated capacity of compressor. 

| ton =$1100 4 tons = $1500 

1 ton = 1200 6 tons= 1700 

2 tons= 1350 8 tons= 2000 

Ice water pipe, valves and fittings in place, including cork 
covering, hangers, floor and wall plates, cutting in new buildings, 
etc., per foot of pipe. 



Galv. 


Brass 


i-inch = $0.55 


$0.85 


|-inch = 0.65 


0.95 


1 -inch= 0.75 


1.15 


11-inch = 0.85 


1.45 


H-inch= 0.97 


1.70 



Galv. 


Brass 


2 -inch =$1.10 


$2.10 


2|-inch= 1.30 


2.70 


3 -inch= 1.60 


3.60 


3£-inch= 1-85 


4.50 


4 -inch= 2.15 


5.20 



The first column above is based on galvanized iron pipe and 
fittings and the second column is based on iron pipe size brass 
pipe and cast brass fittings. 

None of the estimates above include any portion of the drain- 
age systems to which the fixtures in question are connected. 

SPECIFICATION 

There follows a typical specification which is the uniform type 
used by the Supervising Architect's office. 

The drinking fountains, drain pipings, etc., are specified in con- 
nection with the plumbing fixtures and waste water systems 
respectively. 

Drinking-water system. This contractor must furnish and in- 
stall complete in every detail a drinking-water system to provide 
cooled water at the various drinking fountains and ice-water 
faucets in the building. 

General arrangement. The apparatus and appliances to be lo- 
cated where shown on drawings and as directed, with refrigerat- 



174 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

ing machine, condenser, cooling tank, circulating pump, etc., in 
the basement, equalizing tank in attic, and fountains and faucets 
throughout the building. 

Water-supply and waste connections. Where shown on drawing 
a connection provided with a gate valve to be made to water 
main at basement ceiling. Water-supply pipes of proper size to 
be made to the various parts of the apparatus, i. e., condenser, 
cooling tank, compressor, etc., and each connection to have a gate 
valve. This pipe to be same as other cold-water pipe installed 
under this specification. 

Overflow from condenser and compressor jacket to be run and 
discharged over engineer's sink, unless otherwise shown on draw- 
ings. A cesspool with a running trap to be placed in proper 
location to receive overflow and drain from cooling tank herein- 
after specified. 

Drinking water piping system. The drinking water piping system 
to start from the pump in basement and run along basement ceiling 
with branches and risers of the sizes noted. Risers to continue 
up to attic and be collected together in attic and run and con- 
nected to opening in or near bottom of equalizing tank hereinafter 
specified. 

The return main to be taken from tap in or near top of equal- 
izing tank and be run down stack and to discharge into cooling 
tank. Each rising line in basement and corresponding line in 
attic and run-out to each fountain or faucet on first floor and 
basement to have a gate valve. Kind of pipe, covering, hangers, 
etc., to be as hereinbefore specified in connection with water supply 
system. 

Refrigerating machines. Machines using either ammonia, sul- 
phur dioxide, carbon dioxide, or ethyl-chloride may be used, and 
must be of compression type. Machine shall be of sufficient ca- 
pacity to remove not less than — British thermal units per hour 
from the circulated drinking water. This is the net work to be 
performed in the cooling tank exclusive of all transmission and 
radiation losses in machine, tank, etc. 

Compressor shall be of rugged construction and shall be ar- 
ranged to reduce as far as practicable the possibility of escape of 
refrigerant into building. Reciprocating compressor may be 
inclosed in a sealed metal chamber forming condenser and liquid 



PLUMBING, DRAINAGE AND WATER SUPPLY 175 

receiver, may have cylinder immersed in same chamber with con- 
denser, or may have cylinders inclosed in independent water 
jacket. No stuffing boxes will be permitted except on crank 
shaft. Crank cases to be inclosed joints between covers, and 
crank cases to be ground to perfect fit without the use of any 
gaskets. Pistons shall have sufficient number of snap rings to 
prevent leakage of refrigerant. Valves shall be ground to fit 
seats and provided with steel springs. Rotary compressors 
shall have gears inclosed and run in oil. 

Lubrication of compressors shall be by splash system, and suit- 
able oil eliminator shall be provided on discharge from compressor. 

There shall be a safety valve or other approved appliance to 
open into the low-pressure side when the pressure at the discharge 
valve exceeds a certain predetermined pressure fixed by the 
manufacturer. 

The machine used to be mounted on a cast-iron bed plate on a 
suitable brick or concrete foundation provided by this contractor 
and to be driven by a mot or of ample size wound for — volts — 
current by means of double oak tanned leather belt or approved 
noiseless chain belt. Motor to be in accordance with specifica- 
tion hereinafter for " Motors." 

In event machine having pipe or coil condenser is used it shall 
have a by-pass of proper size and properly valved to enable 
compressor to pump out the condenser. 

Bearings of machine used to be of ample size and lined with best 
quality antifriction metal. 

Machine used shall have name of manufacturer cast on or a 
brass name plate riveted on. The name of contractor or dis- 
tributing agent will not fulfill this requirement. 

Expansion chamber. In event of a machine having compressor 
in sealed metal chamber, an expansion chamber shall be con- 
nected thereto and be arranged to be partly submerged in the 
water of cooling tank. 

Condenser. Condenser shall contain ample surface to insure 
minimum water consumption and medium head pressure with 
condensing water at 70° F. Condenser may consist of a sealed 
chamber containing compressor, which is enclosed in a metal 
receptacle, with cover, and partly submerged in condensing 
water. Condenser may be a coil of extra heavy pipe submerged 



176 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

in chamber forming cylinder jacket or in a separate water chamber, 
or may be a double pipe condenser. 

Pipe shall be special ammonia piping coils and shall have 
welded joints. Double pipe condensers shall be made up with 
extra heavy special fittings. Double pipe condenser to be suit- 
ably mounted where shown on drawings or directed. Flow of 
condensing water shall be in opposite direction from that of re- 
frigerant. Condenser shall be connected to water supply and 
overflow to sewer as hereinbefore specified. 

Liquid receiver. Liquid receiver to be of ample capacity and 
may be formed in sealed chamber inclosing compressor, may be 
in base of compressor, or may be of extra heavy wrought iron 
with welded heads fitted with gauge glass safety cocks and inlet 
and outlet valves. 

Expansion coil. The expansion coil, if used, to be placed in 
tank hereinafter specified, shall be spiral in form and shall con- 
tain an ample amount of proper size extra heavy wrought-iron 
pipe with welded joints and galvanized after welding. 

Cooling tank. Cooling tank shall be of the open type, con- 
structed of 3^-inch galvanized iron — feet inside diameter and — 
feet high, with lj-inch angle iron around top and bottom; rivets 
to be f-inch in diameter and spaced not over If inches apart. 

All openings in tank for pipe connections shall be provided with 
standard screw flanges riveted on or with reinforced openings. 
Tank shall be provided with a — inch drain opening and — inch 
overflow opening. Overflow and drain openings to be piped to 
cesspool hereinbefore specified and the latter to have a gate valve. 

Tank shall rest upon an insulated bottom supported on the 
basement floor. The insulating base to rest upon concrete base 
6 inches high, built on basement floor and extending 3 inches out- 
side of insulating base all around. The insulation shall consist 
of one course of lj-inch thick cork laid in hot asphalt; a second 
course of cork 1J inches in thickness to be laid in hot asphalt 
directly on top of the first course; all joints shall be made tight 
and top course flooded with hot asphalt. The insulation shall 
extend to back side of outer sheathing of sides of tank and edges 
covered with asphalt. 

The sides of the tank will be insulated with granulated cork 
well tamped, not less than 8 inches thick at any point, and held in 



PLUMBING, DRAINAGE AND WATER SUPPLY 177 

place by suitable outer casing constructed of J-inch T. & G. 
sheathing, top edge to be carried up to underside of f-inch sheath- 
ing on the top of cover, and edge to be covered with asphalt. 
Sheathing to extend to top side of outer cover of top, as herein- 
after specified, and down to concrete base on bottom. Three 
bands made of No. 14 Brown & Sharpe gauge brass 1J inches 
wide to be placed on tank and held in place with brass screws. 
Sheathing to be held in place independent of the brass bands. 
A quarter round to be placed around bottom of tank. Top edge 
of tank to be finished with a neat wood molding around same. 

The top of the cooling tank will have an outer cover of f-inch 
T. & G. sheathing backed with 3-ply insulating paper, 1J inches 
of cork board covered with asphalt and backed with f-inch T. & 
G. sheathing, top cover to be provided with access opening fitted 
with lid; lid shall be of the same general construction as the top 
and shall be fitted with lifting ring and brass hinges. Entire top 
of tank to be easily removable to permit removal of expansion 
coils. 

Balancing tank. There shall be furnished and installed in the 
attic a galvanized sheet-iron equalizing tank, — diameter by — ■ 
feet high. Tank shall be constructed of 3%-inch galvanized- 
steel plates and shall have a — inch opening in the shell near the 
top for the return pipe to the cooling tank, a — ■ inch opening above 
the opening for the return pipe to serve as an auxiliary overflow 
to waste pipe as shown on plans, and a — inch opening in bottom 
for connection to risers from pump; openings shall be properly 
reinforced to receive pipe connections. Tank to have a clean-out 
handhole in one end and have flat heads. 

The tank to be suspended from roof construction or carried on 
supports made of pipe and malleable-iron fittings, as directed by 
superintendent. 

Tank to be insulated on shell and ends with two thicknesses 
of 2-inch best quality cork board, pressed to fit shell of tank. 
Cork board to be put on with asphalt with all joints staggered. 
Cork board to be covered with 12-ounce duck securely sewed on 
and painted two coats asphaltum paint, and held on with brass 
bands 1 inch wide of No. 14 Brown & Sharpe gauge placed 12 
inches apart. Insulation of heads to be held in place by circular 
sheets of No. 18 galvanized iron under the canvas covering. 



178 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

Circular sheets to be held in place by four-worm wire stays ex- 
tending from end to end of tank. Galvanized-iron end sheets to 
be suitably reinforced where necessary. A neat removable sec- 
tion to be made for access to handhole. Edges of opening for 
this purpose to be protected by a galvanized-iron thimble flanged 
inside of cork and soldered to circular sheets. 

Woodwork. All woodwork in connection with cooling tank to 
be hard pine or cypress. 

Circulating pump. Furnish and erect where shown on plans one 
triplex pump capable of circulating not less than — gallons of 
water per minute through the piping system, at not exceeding 50 
revolutions per minute. Pump to have brass plungers operating 
through approved stuffing boxes. Cylinders to be brass lined 
and pump to be brass fitted throughout. Crank shaft and con- 
necting rods to be cast steel or forged. Bearings to be lined with 
best quality antifriction metal and be provided with sight-feed 
lubricating devices. 

Pump to be driven by an electric motor through an approved 
noiseless chain belt of ample size and strength. Pump and 
motor to be set on one cast-iron sub-base on a suitable brick or 
concrete foundation provided by this contractor. 

Suction and discharge connections to have gate valves near 
pump and discharge connections to have check valve. Air chamber 
of proper size to be placed on discharge connection near pump. 
Motor to be in accordance with specification hereinafter for 
" Motors." 

Alternate circulating pump. In lieu of a triplex pump contrac- 
tor may furnish and install an approved screw pump of same ca- 
pacity. Pump to have four cast-bronze or cast-brass screws or 
impellers. Pump to be brass fitted throughout. Bearing to be 
of ample area lined with best quality antifriction metal. Supply 
and discharge connections to be so made in relation to location 
of screws that there will be no end thrust. Brass stuffing boxes 
to be on suction screws. Screw pump to be direct-connected to 
motor by a flange coupling. Motor and pump to rest on one 
cast-iron sub-base mounted on a suitable brick or concrete foun- 
dation furnished by this contractor. Motor to be in accordance 
with specification hereinafter for " Motors." 

Pump suction and discharge connections to have gate valve 
near pump, and discharge connection to have a check valve. 



PLUMBING, DRAINAGE AND WATER SUPPLY 179 

Gauges. Pressure gauges shall be provided on both high and 
low pressure sides of the system and shall be mounted on cast- 
iron gauge boards secured to wall or column where directed by 
superintendent. 

Gauges to have not less than 6-inch dial, iron body, and polished 
brass rim, and in accordance with the following requirements: 
Pinion, pinion staff, sector staff, and hairspring to be constructed 
of either nickel, phosphor-bronze, Tobin bronze, or German silver; 
solid, not plated. In addition, the top and bottom plates must 
be made of one of the above-named metals, solid, or of brass or 
steam metal with substantial bushings of one of the above-named 
noncorrosive metals. Levers, slides, and their adjusting and 
pivot screws may be made of brass or steam metal. 

If the machine is enclosed in a sealed metal chamber no gauges 
will be required. 

Jointing, etc. All joints in refrigerant piping to be tinned and 
soldered in a workmanlike manner. Refrigerant piping to be 
painted as hereinafter specified for pipes in heating system. The 
contractor must furnish all material for charging the apparatus 
ready for operation. 

Thermometers. Two thermometers with a range from zero to 
100° to be installed in the drinking-water line near the tank, one 
to be installed in the flow and one in the return line. 

Float valve. An approved 1-inch diameter float valve to main- 
tain water level 2 inches above top of expansion coils must be 
installed in the drinking-water cooling tank and connected to the 
water piping. 

• Covering. Water supply pipes and condenser overflow to be 
covered as hereinbefore specified for cold-water pipe. Covering 
for ice-water pipe is hereinbefore specified. All refrigerant pipe, 
valves, and fittings on the "low" side to be covered same as 
hereinbefore specified for ice-water pipe. Overflow from balanc- 
ing tank to be covered same as other ice-water pipe. 

Motors for direct current. Motors to be wound for — volts 
direct current. To be of design adapted to service and must 
be capable of developing the required power and of withstanding 
temporary overloads of at least 50 per cent. Bearings to be of 
the self -oiling type. Motor must be designed to operate practi- 
cally without noise. 



180 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Speed of motor for compressor must not exceed five times that 
of compressor. 

Field coils must be form wound and so secured that they may be 
readily removed without unwinding. Armature must have slotted 
core, with windings thoroughly insulated and secured firmly in 
place. It must be balanced both mechanically and electrically 
and be well ventilated and easily removable. 

Commutator to be of drop-forged or hard-drawn copper of 
highest conductivity, insulated with mica or micanite of even 
thickness and proper hardness to insure uniform wear, and must 
run free from sparking or flashing at the brushes at any load up 
to specified full load or during change of load. It must have 
ample bearing surface and radial depth for wear. 

Brushes to be of carbon of such cross-sectional area as will not 
cause sparking, burning, or blackening of commutator at load 
specified. Brush holders to be of such design that no chattering 
will result from continuous use. Collective adjustment of brushes 
to be made by means of rocker, and individual brush tension is 
to be maintained by a spring. If the motor is of the interpole 
type, the rocker arms may be omitted. 

The frame of machine must have an insulation resistance from 
the field coils, armature windings, and brushes of not less than 1 
megohm. Motor must be capable of standing a breakdown test 
of 1,500 volts alternating current for one minute. 

Motor is to be run continuously at full load for six hours, and 
at the expiration of that time the temperature of the armature 
and fields shall not exceed 50° C. and of the commutator 55° C. 
above the temperature of the surrounding atmosphere. Tem- 
perature to be measured by thermometers shielded by cotton 
waste in a manner approved by department's agent. 

For alternating current. Motors to be wound for — volts, — 
phase, — cycle, alternating current. Motors to be of induction 
type with rotating secondaries of ample power to perform the 
work required and capable of withstanding momentary overloads 
of 50 per cent. 

Compressor motor shall have phase-wound rotor with slip rings 
for inserting starting resistance. 

Circulating pumps motor shall have squirrel-cage 

rotor. 






. 



PLUMBING, DRAINAGE AND WATER SUPPLY 181 

Insulation. Each motor must have an insulation resistance 
between stator windings and between stator windings and frame 
of at least 1 megohm. The insulation must be capable of with- 
standing a breakdown test of 1,500 volts alternating current for 
one minute. 

Heating. After a continuous run at full load for six hours the 
rise in temperature of any part of the windings or frames of 
motors must not exceed 50° C. above the temperature of the sur- 
rounding atmosphere. Temperature to be measured by ther- 
mometers shielded by cotton waste in a manner approved by the 
department's agent. 

Controlling panels. Controlling panels shall be constructed of 
polished black slate, treated to prevent absorption of moisture, 
not less than f inch thick. Panels containing fuses, switches, and 
circuit breakers shall be mounted flush with rheostat panels. 
Panels shall be secured to angle-iron wall frames wherever suit- 
able wall or column is available near motor to mount said panel. 
When no such support is available panel shall be secured to angle 
or pipe floor stand. 

All resistances and other appliances on rear of panels shall be 
sufficiently inclosed to prevent the insertion of a hand into space 
occupied by such resistance. All panels shall be mounted with 
bottom not less than 1 foot above floor. All connections and re- 
sistances shall be mounted on the back of panels and all moving 
contacts to be on front of panels. All angles and pipe braces in 
connection with panels to be enameled black. 

For direct current. Panel for compressor shall have mounted 
thereon one double-pole overload circuit breaker with laminated 
main contacts, auxiliary carbon break of the independent arm 
type of proper capacity to protect motor, and one hand-starting 
rheostat with no voltage release. 

Panel for circulating pump shall have mounted thereon one 
double-pole, single-throw knife switch with enclosed indicating 
fuses of proper capacity and one hand-starting rheostat with no 
voltage release. 

For alternating current. Panel for compressor motor shall have 
mounted thereon one — pole overload and no voltage release 
circuit breaker of the independent arm type and one starting 
resistance of proper capacity. 



182 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

Panel for circulating pump shall have mounted 

thereon one — pole, double-throw knife switch without fuses on 
starting position and with enclosed indicating fuses of proper 
capacity to protect motor from overload on running position. 
Switch must be provided with means to prevent same being left 
in starting position. 

Electrical connections. Conduit and wiring to the panels will 
be provided under the " Conduit and Wiring" section of this 
specification. 

All connections between motors and panels hereinbefore speci- 
fied must be made by this contractor. All conductors are to be 
run in steel conduit terminating in approved condulet type fit- 
tings except such connections as may be so short as to be self- 
supporting, and these must be fully protected from abrasion or 
other mechanical injury. Conductors must be rubber-covered, 
well-tinned, soft-drawn copper of highest conductivity, made in 
strict accordance with the National Electrical Code, and must 
have a distinct marking of the makers. All conductors, No. 8 
Brown & Sharpe gauge and larger, are to be stranded and con- 
nections made by soldering wires in cup lugs. No joints or 
splices will be permitted in feeders except at outlets. Wiring 
system must test free from short circuits or grounds, and the 
insulation resistance between conductors and between conductors 
and ground must not be less than 1 megohm. 

Where size of conductors is not given, the capacity must be such 
that the maximum current carried will not exceed the limits pre- 
scribed by the National Electrical Code. 

Wrenches. A complete set of wrenches for refrigerating ma- 
chinery is to be furnished and mounted in a suitable hardwood 
frame, located where directed by the custodian. 

Refrigerant connections. All necessary refrigerant-piping con- 
nections required for the complete installation must be furnished 
and installed by this contractor, including fittings, valves, gauges, 
purge connections, scale traps, receivers, oil separators, etc. 

The pipe lines shall be provided with heavy flange union con- 
nections to permit removal of any parts without disturbing or 
cutting pipe. All pipe in refrigerant lines shall be extra heavy, 
special black ammonium pipe, and all fittings to be extra heavy 
mild-steel ammonia fittings unless otherwise specified in connec- 
tion with type of machine. 



PLUMBING, DRAINAGE AND WATER SUPPLY 183 

Stop valves to be screw ends, bolted bonnets, extra heavy 
ammonia valves. Expansion valves to be of the needle-point 
type. 

Painting. The machine, motors, and pump to be rubbed down 
and painted one coat before leaving shop and after erection with 
one additional coat of lead and oil paint of tint approved by 
superintendent. 

Piping to be painted same as steam pipe. Cooling tank to be 
filled and rubbed down and given two coats of hard oil. Paint- 
ing for cork covering is hereinbefore specified. Balancing tank 
in attic to be painted two coats heavy asphaltum paint. 

Tests. All water piping in connection with this apparatus to 
be tested as hereinafter specified for water pipe. All refrigerant 
piping must be tested to a hydrostatic pressure 50 per cent greater 
than the actual working pressure, and must be tight under this 
pressure. 

Operating test. After the complete installation the capacity 
of the plant will be determined by a trial of the unit, to be made 
in the presence of and under the direction of a representative of 
the Supervising Architect. 

A temporary connection between a hot-water line and cold- 
water supply to tank if necessary must be made by the contractor 
so that the water used can be obtained at about 75° F. A tem- 
porary draw-off connection must be made by the contractor so 
that water in drinking-water cooling tank can be drawn off from 
bottom of tank and weighed at the draw off. 

A test will be run for a period of not less than 8 hours, as fol- 
lows : The machine and circulating pump will be stopped. Drain 
all water from tank and remove all ice from coils. Fill tank to 
level established by float valve with water at a temperature of 
about 75°F. Then start machine and run under normal condi- 
tions until thermometer in draw off near the tank indicates 40° 
F. Readings to be taken as soon as this temperature is reached, 
which will be starting point of the test. The equipment to be 
run under starting conditions during the test and difference in 
temperature between readings in inlet and outlet to tank multi- 
plied by pounds of water drawn off will represent the work in 
British thermal units. At the expiration of test allowance will 
be made for ice formed on coils as hereinafter explained. At 



184 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

once on completion of test all water will be drained from the tank 
and drain closed and left closed until all ice has melted off the 
coils, the resulting water will be weighed and added to work in 
water cooling above mentioned at the rate of 144 B.t.u. per 
pound of melted ice. The total B.t.u. thus obtained will repre- 
sent the net work performed by the plant. No allowance will be 
made for loss in radiation through tank and connections. During 
the test the temperature of water at the pump suction is to be 
maintained at approximately and not exceeding 40° F. 

Should the net work performed be less than that hereinbefore 
required, the Supervising Architect shall have the right to reject 
the entire apparatus or any part thereof and require the contrac- 
tor to furnish a machine that will fulfil the requirements of this 
specification without additional expense to the Government. 

All expenses of such tests, except such as hereinbefore provided 
under " Inspections and tests," to be paid for by the Government, 
must be paid by the contractor. 

TESTS OF PLUMBING AND DRAINAGE SYSTEM 

Special precautions are taken to insure that all parts of the 
plumbing and drainage system are free from defects and leaks, 
and the following specification requirements are prescribed with 
that in view: 

The entire system of soil, waste, drain, and vent piping, includ- 
ing the interior downspouts and rain-water drainage system, must 
be tested with water or air, as hereinafter described and proved 
tight to the satisfaction of the superintendent of construction 
before the immediate connection is made to city sewer, trenches 
back filled, piping covered, or fixtures connected. 

Either the water or the air test may be used, except when 
there is danger from freezing, when the test must be made with 
air. 

Wooden plugs are not to be used in making the tests. 

The connections between the building and the city sewer and 
the drainage system below the basement floor are to be tested 
separately. 

Water tests. If tests are made with water, the connection 
from the building to the city sewer and the drainage system 



PLUMBING, DRAINAGE AND WATER SUPPLY 185 

below basement floor are each to be filled with water to top of a 
vertical section of pipe 10 feet high, temporarily connected to the 
highest point on the lines to be tested, and the water allowed to 
stand at least 30 minutes for inspection, after which, if the lines 
prove tight, the water is to be drawn off, immediate connection 
made with city sewer, and trenches back filled. 

The soil, waste, drain, and vent piping, the interior down- 
spouts, and rainwater drainage system above the basement floor 
line must have the openings plugged where necessary and the 
piping system above basement floor filled with water to the level 
of the main roof gutters and allowed to stand at least 30 minutes 
for inspection, after which, if the lines prove tight, the water is 
to be drawn off and the fixtures connected. Each vertical stack 
above basement floor with its branch waste and vent pipes may 
be tested separately by inserting plugs in the cleanouts at base 
of verticals in lieu of filling entire system in building with water. 

Air tests. If tests are made with air, a pressure of not less than 
10 pounds per square inch, equal to 20 inches of mercury, must 
be applied with a force pump, and said pressure maintained at 
least 15 minutes without leakage. 

A mercury column gauge must be used in making the air tests. 
Testing instruments must be furnished by the contractor. 

Smoke test. After fixtures have been connected, a smoke test 
must be applied to the sanitary system, and the entire system 
proved tight, to the satisfaction of the superintendent, when 
filled with smoke under pressure equal to 1 inch of water. The 
smoke machine must be provided by the contractor. 

Test of water-supply system. At completion of the work, 
except application of the non-conducting coverings, the waste- 
supply system must be tested to a hydrostatic pressure of 100 
pounds to the square inch. 

Any water piping run in chases in walls must be tested to 
above pressure and proved tight before the chases are covered. 
The test pump must be provided by the contractor. 

Cost of tests and certificate. Cost of tests to be borne by the 
contractor, who must furnish the office, through the superin- 
tendent, with a certificate that the required tests have been 
satisfactorily made. 

Certificate must be countersigned by the superintendent, who 
will forward same to the Supervising Architect. 



186 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

ESTIMATING DATA FOR PLUMBING AND DRAINAGE SYSTEMS 

After the drawings for a plumbing, drainage, and water-supply 
system are prepared an approximation of cost must be made in 
order to be able to determine whether the proposals later ob- 
tained for the work are reasonable; and the following data, which 
will generally give results within 5 to 10 per cent of the lowest 
proposals received, are used: 

New building, approximate cost complete plumbing sys- 
tem, not including marble finish for all toilet-rooms, 
average per fixture ' $125 .00 

Old building, approximate cost complete new plumbing 
system, including marble finish for toilet-rooms, aver- 
age per fixture 200 .00 

For estimate on the above basis count as one fixture each : 
Shower-bath. 
Water-closet. 
Slop sink. 

Water heater (with hot-water tank). 
Urinal. 
Lavatory. 
Small sink. 
Interior downspout. 

Fire-hose connection with hose and rack complete. 
Drinking fountain with ice box. 
Four wall hydrants. 

Cost of system is divided approximately as follows: 

"Roughing in," per fixture 50.00 

Marble work, per plumbing fixture 75.00 

Fixtures, average each 50 . 00 

Additional for removal of work in place, and for cutting 

and repairs in old buildings, per fixture 25.00 

If brass water pipe is used throughout the job add $20.00 
per fixture to above figures. 

Itemized estimating data. If a very close approximation of 
the cost of plumbing and drainage system is desired, all pipe, 
fittings, valves, and fixtures should be taken off the plans and 
specifications, and the following unit prices used: 

Vitreous corner lavatory, with back, including connec- 
tions and trimmings as described above, complete in 
place $35.00 

Special ice-box, complete in place 160 . 00 



PLUMBING, DRAINAGE AND WATER SUPPLY 187 

Portable type combination water cooler and drinking 

fountain, in place $150.00 

Vitreous corner lavatory, with back, including connec- 
tions and trimmings as described above, complete in 

place 36.00 

Bubbling fountain, pedestal or wall type, complete in 

place 32 .00 

Vitreous slop sink with trimmings, complete in place. . . 65.00 

Enameled-iron sink, complete in place 22.50 

Fire-hose rack with 75 feet of 2-inch hose, complete in 

place 33 .00 

Roof connections complete in place for down pipes from 
gutters or for vent stacks: 

2-inch diameter 5 .00 

3-inch diameter 5 . 25 

4-inch diameter 5 .80 

5-inch diameter 6 .00 

6-inch diameter 7.00 

Four-inch lead bend with ferrule, complete in place, for 

basement closet connection 3.00 

Three-inch lead bend with ferrule, complete in place for 

basement slop sink connection 2.75 

2-inch lead bend, etc 2 .00 

Cast-iron water heater with 12-inch grate and 18-inch x 
60-inch galvanized steel storage tank, with copper or 
brass steam coil, automatic temperature regulators, and 
all trimmings, smoke connection, etc., complete in place, 

including nonconducting covering 180.00 

Outfit as described above, without steam coil 160.00 

Automatic gas water heater with capacity of four gallons 
per minute, and steel tank with steam coil as described, 

complete in place 250.00 

Shower-bath fixture with floor drains, soap dish, coat 

hooks, seat, etc., complete in place 60.00 

Anti-freezing wall hydrant or street washer, in place. ... 10.00 
Excavations for pipe trenches inside of building: 

Trench 3-feet inch deep, per lineal foot 0.15 

Trench 4-feet inch deep, per lineal foot 0.25 

Excavations for pipe trenches outside of building, trench 
with average width 3 feet inch and average depth 12 

feet inch, in ordinary soil, per lineal foot 1 .00 

Excavations in rock, per cubic yard 3 .00 

Repairing streets, allow to cover any kind of work: 

Per square foot . 30 

Per lineal foot of trench 1 . 00 

Street manhole and running-trap manhole, with cast-iron 
frame and cover, complete in place 75 . 00 



188 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Brick manhole, 18-inch x 30-inch, in basement floor, with 

cast-iron frame, and cover, complete in place $30.00 

Area cesspool, complete in place 1 .50 

Single-hub running trap, with cleanout plug, complete in 

place 3.00 

2-inch 3.00 

3-inch 4.00 

4-inch 4.50 

5-inch 5.00 

Siphon-jet water-closet, 54-pound bowl, with porcelain 
tank and connections, floor flange, coat hooks, toilet- 
paper holder, etc., complete in place 40.00 

Siphon-jet urinal with porcelain tank, outlet flange, etc., 

complete in place 30 . 00 

Porcelain stall urinal with porcelain tank and trimmings, 

complete in place 60 . 00 

Vitreous rectangular lavatory, 24-inch x 20-inch, with 
faucets, nonsiphoning trap, supply and waste connec- 
tions to wall or floor, compression stops and air cham- 
bers on supplies, and with towel rack, complete in place. 40 . 00 
For special combination hot and cold water faucet, ice 
water faucet, and tumbler holder on lavatory, add for 

each lavatory so equipped 5 . 00 

Compound type water meter including heavy locked 
meter cock or gate valve, and three gate valves, f-inch 
drain valve and galvanized pipe connections and fit- 
tings complete in place. 

2-inch 75.00 

With brass pipes and cast iron fittings 85.00 

3-inch 150.00 

With brass pipes and cast iron fittings 175.00 

4-inch 225 .00 

Heavy iron body water pressure regulating valve, in- 
cluding three gate valves, two pressure gages, strainer 
fitting and galvanized iron pipe connections and fittings 
complete in place: 

i-inch 15.00 

l|-mch 38.00 

2 -inch 52.00 

3 -inch 80.00 

With brass pipe and cast iron fittings: 

Hnch 17 .00 

11-inch 44 .00 

2 -inch 62.00 

Rough cast brass downspout nozzles in place including 

cutting of hole and nipple through wall: 

2-inch 5.00 






PLUMBING, DRAINAGE AND WATER SUPPLY 189 

3-inch $6 . 00 

4-inch 7.00 

5-inch 8.00 

6-inch 9.00 

Automatic water operated ejector in place complete and 

ready for operation: 

1 -inch 50.00 

U-inch 65.00 

Rodding cleanouts on cast iron pipe below basement floor 

including fitting in main drain or on cast iron drain 

outside of building: 

3-inch 2 . 30 

4-inch 2.90 

5-inch 4.00 

Cleanout fittings with heavy brass plug and nickel plated 

cover plate in place: 

2-inch 1 .80 

3-inch 2.75 

4-inch 5.00 

5-inch 8.90 

6-inch 12.00 

Screw jointed cleanout fitting with heavy brass plug in 

place: 

2-inch 1.20 

3-inch 3.25 

4-inch : \. . 4.50 

5-inch 7.65 

6-inch 15 . 00 

Balanced type back water valves complete with gate 

valve and 25 feet of f-inch brass vent piping including 

galvanized fitting in vent stack in place exclusive of 

manhole: 

3- and 4-inch 20.00 

6-inch 25.00 

• The following table gives cost in place of galvanized mild steel 

pipe, recessed drainage fittings, etc. Threads included in price of 

fitting. Fittings are long radius. For valves, hangers and plates 
see schedule for heating work. 



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190 



PLUMBING, DRAINAGE AND WATER SUPPLY 



191 



For hangers, valves, black fittings for vent pipes, etc., see heating 
schedule. When using heating schedule for fittings, etc., for plumbing 
work add cost of threads to same. 

Double-hub running trap with cleanout plug and fresh-air 
inlet, complete in place: 

6-inch $10.00 

8-inch 18.00 

Extra heavy cast-iron soil pipe and fittings in place, exca- 
vation not included: 



Diameter 

Inches 


Pipe per lineal foot 


Elbow, any turn 


T, Yor45° Y 
branch 


2 


$0.20 


$1.10 


$1.25 


3 


0.30 


1.40 


1.75 


4 


0.40 


1.80 


2.00 


5 


0.50 


2.25 


2.50 


6 


0.65 


2.75 


3.25 


8 


1.10 


6.50 


5.50 


10 


1.35 


7.25 


10.00 


12 


1.70 


11.00 


13.50 


15 


4.00 


20.00 


26.00 



Pipe and fittings in place, for water supply, 
of pipe. Exclusive of hangers, cutting, etc. 



Threads included in cost 



Size, inches, diameter 

Galvanized mild steel pipe 

Galvanized malleable ells 

Galvanized malleable tees 

Brass unions 

Gate valves (brass) 

Iron pipe size brass pipe (rough) 

Cast brass ells (rough) 

Cast brass tees (rough) , 



1 

4, 


3 

8 


i 

2 


3 

i 


1 


li 


If 


$0.10 


$0.10 


$0.10 


$0.11 


$0.13 


$0.17 


$0.20 


0.11 


0.13 


0.15 


0.17 


0.26 


0.28 


0.40 


0.15 


0.17 


0.20 


0.22 


0.35 


0.39 


0.53 


0.25 


0.30 


0.40 


0.50 


0.65 


0.85 


1.20 


0.65 


0.70 


0.80 


1.00 


1.35 


1.80 


2.40 


0.20 


0.23 


0.29 


0.37 


0.48 


0.69 


0.83 


0.13 


0.15 


0.18 


0.22 


0.33 


0.41 


0.55 


0.19 


0.23 


0.29 


0.34 


0.53 


0.65 


0.88 



2 
SO. 25 
0.55 
0.70 
1.70 
3.47 
1.10 
0.80 
0.98 



For finished brass nickel plated pipe and fittings in place take twice 
the above for rough brass. 



CORK COVERINGS 



The following table gives cost of standard ice water thickness 
cork covering li-inch thick in place on ice water lines (exclusive 
of pipe) including canvas, bands and painting. 



Pipe size, in. diameter. . 

Pipe per foot 

90° or 45° elbow 

Straight or reducing tee 
Valves 



1 

4 


3 

8 


i 

2 


3 
4 


1 


H 


n 


2 


2| 


3 


3§ 


$0.33 


$0.37 


$0.42 


$0.45 


$0.54 


$0.61 


$0.70 


$0.78 


$0.87 


$0.95 


$1.08 


0.45 


0.50 


0.55 


0.61 


0.70 


0.78 


0.87 


0.95 


1.03 


1.18 


1.32 


0.50 


0.58 


0.61 


0.70 


0.78 


0.87 


0.95 


1.13 


1.19 


1.32 


1.53 


0.55 


0.61 


0.70 


0.78 


0.87 


0.95 


1.03 


1.15 


1.32 


1.56 


1.71 



4 

$1.20 

1.52 

1.77 

2.05 



192 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



For long radius fittings, doable the prices for fittings given above and 
add 10 per cent. 

Standard brine covering (2 inches to 3 inches thick according to pipe size) 
costs 15 per cent more in place than standard ice water thickness. 

The following table gives cost in place of vitrified, salt glazed 
sewer pipe, with cemented joints, exclusive of excavation, back- 
filling or any special conditions met in exceptional soil. 



Diameter, inches. . . 

Pipe per foot 

Y branches 

Elbows (any angle) 
Increasers 



4 


5 


6 


8 


10 


12 


14 


$0.17 


$0.20 


$0.23 


$0.29 


$0.41 


$0.53 


$0.68 


0.80 


0.90 


1.00 


1.30 


1.80 


2.25 


2.90 


0.70 


0.80 


0.90 


1.25 


1.65 


2.15 


2.80 


0.70 


0.80 


0.85 


1.10 


1.50 


1.90 


2.40 



15 
£0.75 
3.20 
3.20 
3.20 



Nonconducting felt covering for hot and cold water pip- 
ing, take 70 per cent off the a 22-cent" list for cost of 
covering in place complete. 
Terrazzo floor in place, including concrete bed, per square 

foot $ 0.50 

Removing old floors and laying new concrete base and 

terrazzo floor, per square foot 1.25 

Marble floor slabs, 2-inch thick, per square foot in place. . 1.50 
Free standing marble, 1| inches thick, per square foot in 

place 1 .25 

Marble wainscot, f-inch thick, per square foot in place. . . 1.00 

Marble coved floor borders, per lineal foot in place 1.50 

Plain marble tile floor . 75 

Nickel-plated brass standards, bracing, angles, etc., in 
place for marble work in toilet-rooms: 

For water-closet inclosure 18.00 

For water-closet stall in carriers' toilet 4.50 

For urinal stall 4.50 

For shower-bath inclosure 18.00 

Cleaning and painting walls of toilet-rooms three coats lead 
and oil, per square foot 0.30 

Especial attention is called to the fact that the foregoing figures 
are correct for certain special conditions in new Federal buildings, 
but are not applicable under all conditions. Used with judgment 
they will give accurate results. 



CHAPTER V 

GAS PIPING 

The practice of the office is to install a complete gas piping sys- 
tem in every building, except in a few of the larger cities, both for 
emergency use and to serve as a check on the cost of electric 
current supplied by local lighting companies, and while the system 
costs less than any other portion of the mechanical equipment, 
it gives more trouble than all the rest of the work. Specifications 
are carefully drawn, and repeated and strict tests are imposed, 
and superintendents of construction and inspectors are charged to 
give special attention to this branch; but with all these precautions 
trouble frequently ensues. 

In making an extension to a building only a few years old it is 
usual to find the gas piping system in a bad condition and filled 
with leaks which are difficult to locate and costly to repair. 

Gas piping in old buildings is tested to only 4 inches of mercury, 
which must stand one hour without perceptible drop. This test 
is made with lighting fixtures disconnected and outlets capped. 

With old fixtures and old piping the test is reduced to 2 inches; 
and with new piping and new fixtures it is made to 3 inches of 
mercury. 

The gas piping system will average $3.00 per outlet in new 
buildings, and if the total piping is measured up, 15 cents per 
foot for all sizes will be about correct. 

The following is a sample specification such as is used for a 
new building: 

SPECIFICATION 

This specification includes the installation of a complete system 
of gas piping for supplying all the gas only and combination out- 
lets indicated on the drawings. 

A gas meter satisfactory to the local gas company must be 
furnished and installed where indicated. 

All the gas outlets (except vault outlets and outlets indicated 
on plans as gas only) to be arranged so as to allow placing on 
same of electric conduit boxes for combination fixtures. 

193 



194 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Contractor to bring into the building a gas supply pipe of size 
noted on drawings, and furnish and place at curb line a stop cock 
or tee-handled gate valve on same, also a cast-iron extension 
stopcock box, located as directed. Gas main just inside of base- 
ment wall to be provided with a brass gas cock. 

Kind of pipe used from street main to inside of building and 
manner of laying same to be in accordance with the regulations of 
the gas company. If the company will not permit installation of 
pipe of size noted on drawing, the contractor must take up the 
matter, before installing the work, with the superintendent, who 
will refer the matter to the Supervising Architect. 

Gas pipes in building to be "standard" gauge galvanized 
wrought-iron or galvanized mild steel, and all fittings to be gal- 
vanized, malleable-iron, beaded fittings. 

Unless otherwise noted or indicated on the drawings the size of 
gas pipes to be as follows: 



Size of pipe 
Inches 


Greatest length allowed 
Feet 


Greatest number ot 
burners 


1 

2 


30 


7 


3 

4 


50 


28 


1 


70 


50 


H 


100 


96 


14 


150 


140 


2 


200 


280 



Main gas pipe of size noted on basement plan to start at point 
indicated, with capped inlet near basement ceiling, run along 
same to vent shaft or lookout shaft as shown. From the main, 
near shaft, a separate riser is to be taken and run up in shaft 
to supply the horizontal branches in each floor. Each separate 
riser is to be controlled by a gas cock, located where indicated on 
plan. 

Insert in main where shown near foot of risers a "T" fitting, 
and a 12-inch piece of pipe of same size as main, with reducing 
fitting, to be placed for the purpose of collecting drip and -scales ; 
a short piece of f-inch pipe with gas cock to be screwed to reduc- 
ing fitting, so that drip can be drawn off when necessary. 

Plugged outlet of size noted on drawing to be provided on gas 
main in basement at point indicated, for connection to special 
furniture fixtures to be placed under another contract. 



GAS PIPING 195 

Gas main to be supported close to basement ceiling with 
wrought-iron or malleable-iron hangers, and risers, except those 
of short length, to be securely supported in an approved manner. 

Branches from pipes run in first floor to brackets in unplastered 
rooms in basement, the gas main in basement, the branch in base- 
ment to post-office screen lights, and all gas pipe in unfinished 
attic or roof space to be run exposed. All other gas pipes to be 
concealed. 

The supply branch to the screen lights to be fitted with a gas 
cock so that supply to said lights can be controlled. Cock to 
be placed where indicated on drawings. 

Bracket lights to be supplied by branches taken from the gas 
piping run in the floor construction of the story in which they are 
located. Bracket lights in basement to be supplied from main 
in first-floor construction. 

Gas outlets for bracket lights to be set approximately 7 feet 
above floor, unless otherwise noted. Supply pipe for post-office 
screen lights to be taken from main near basement ceiling at 
point indicated, and run up concealed in screens and along same 
in space provided for pipes, with outlets at points indicated. 
These outlets will be, in general, about 7 feet above floor. 

The gas outlets for all vaults to be taken from gas pipes below 
floor, and run up in wall alongside of vault doors to a distance of 
5 feet above floor line; outlets to extend just beyond finished 
plaster line, and ends to be capped. 

Gas nipples for fixtures to be at right angles to the walls and 
ceiling from which they project, and to project from finished plas- 
ter line of ceiling not less than f -inch nor more than lj inches, 
and from finished plaster line of walls not less than \ inch nor 
more than } inch, and be properly fitted and capped. This, 
requirement will be strictly enforced. 

No branch pipe from main to be less than \ inch internal 
diameter. 

Outlets for all brackets, vault outlets, and drops for all chande- 
liers to be f-inch diameter. 

Drops for chandeliers must be taken from center of a a T" 
branch; and where a chandelier occurs at the end of a branch, or at 
end of a run of main, the extra opening in the tee to be fitted with 
a capped 12-inch length of pipe to form a proper support for the 
fixture. 



196 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

All gas pipes to be run regularly and in a workmanlike manner, 
using all necessary fittings, and in no case springing or bending 
the pipe to reach a point desired. 

All pipes to be run level where possible, and when necessary to 
be pitched, to grade down toward riser, and to be without traps. 

The use of salt water or any other corrosive substance to make 
piping tight is strictly prohibited. 

Each length of pipe must be hammered and all scale blown out 
before assembling. 

Pipe and fittings to be put together with red lead, litharge or 
any approved compound. 

No gas fitters cement will be allowed except at outlet caps. 

At the beginning of the work when directed by the superinten- 
dent the contractor shall furnish and set up in a readily accessible 
position where directed a test pump and a mercury gauge con- 
nected to the permanent gas piping. Pump and gauge to be 
properly protected and kept in working order until after final 
inspection, when same is to be removed when directed by the sup- 
erintendent. At all times, except when it would be impracti- 
cable on account of gas pipe actually being connected to work 
already in place, a pressure equal to 15 inches of mercury is to 
be maintained on all gas Fines in place. At such times as the 
superintendent may direct, also (1) each time any new work is 
laid, (2) before the last coat of plaster is put on, (3) on completion 
of the plastering, (4) on completion of the finished floors and be- 
fore lighting fixtures are connected, the above pressure shall, 
without pumping, be maintained in the presence of the superin- 
tendent for a period of one hour with drop in pressure during the 
hour not exceeding J inch of mercury. 

Tests to be made by the contractor, at his own expense, and he 
must furnish this office, through the superintendent, with a cer- 
tificate that satisfactory tests have been made. The certificate 
must be countersigned by the superintendent, who will forward 
same to the Supervising Architect. 



CHAPTER VI 

CONDUIT AND WIRING SYSTEMS 

For electric lighting installations in Federal buildings the stand- 
ard arrangement is an underground service connection to an en- 
trance switch in basement just inside of the building. In build- 
ings where only two or three distributing tablets are used the 
entrance switch and the sub-feeder switches are combined in the 
same tablet. In larger buildings, requiring four or more dis- 
tribution tablets, there is installed a sub-feeder tablet from which 
sub-feeder or mains are run to the various distribution tablets 
throughout the building. 

In large buildings where an electrical generating plant may be 
installed at some future time, a standard type of switchboard is 
placed in the engine room with a service connection to the mains 
of the local companies. 

The main service switch is usually located as near as prac- 
ticable to the point at which the feeder circuit enters the build- 
ing, and also near basement entrance door. The sub-feeder tab- 
let or the switchboard is so located as to obtain the best runs and 
the shortest average length (capacities considered) of sub-feeders. 
The point sought for is one at which the sum of the products 
obtained by multiplying the length of each sub-feeder by its 
ampere capacity is a minimum. The location for main service 
switch and sub-feeder tablet or switchboard is selected with due 
consideration to the character of the room, and coal rooms, stor- 
age rooms, and letter carriers' lounging and toilet rooms are never 
chosen. 

The distribution tablets for the post-office section are located 
in the post-office workroom, so that all the lights in the work- 
room and in letter carriers' lounging and toilet rooms, and gen- 
erally in the executive offices of the post office also, can be con- 
trolled from same. All other tablets in the building are located 
in public spaces (corridors or lobbies) or in the basement outside 
of post-office space and storerooms. 

197 



198 MECHANICAL EQUIPMENT OF TEDEKAL BUILDINGS 

The locations sought for distribution tablets are those which 
will admit of reaching same readily with the feeder, and making 
all branches of approximately equal length, the maximum length 
being generally 100 feet. Architectural features of a building 
are also considered. 

The public lobby on first floor and the exterior lights at main 
entrance are controlled by the tablet located in the post office 
workroom, or, in the larger buildings by a tablet located in the 
boiler room in basement. Where not more than three circuits 
are required to supply a floor above or below a given tablet, 
they are taken therefrom. 

Not more than twenty circuits are taken from a tablet, and 
one or more spare switches are provided on each distributing 
tablet. 

In locating distributing cabinets in thin walls care is taken to 
see whether a steel beam is located directly over the cabinet; 
and should this be the case, the structural engineer is requested 
to move the beam or substitute two channels for the beam and 
set the backs of the channels 1\ inches apart. 

A cabinet is never located in a partition wall which is less than 
4 inches thick exclusive of plaster. 

Cabinets containing the distributing panels are of steel, and 
all cabinets and tablets are of special design. 

The tablets are of Blue Vermont marble and the distribution 
tablets contain 30-ampere switches and 10-ampere enclosed fuses 
controlling the various circuits. 

All wiring is run in rigid metal conduits, and all main service 
connections to the building are made underground and usually 
from a steel pole of special design located on the Federal property 
by the government. If special conditions forbid this, an under- 
ground connection is made from the service company's poles ad- 
jacent to the building site. 

The conduits to service company's poles are run up same 10 
feet and provided with a weatherproof hood. The practice of 
the office was formerly to install handhole boxes at the base of 
service poles, but this has been abandoned as unsatisfactory, 
except in special cases. 

The junction box on main feeder conduit inside of basement is 
not made less than 6 inches x 6 inches x 3 inches deep. 



CONDUIT AND WIRING SYSTEMS 



199 



The feeder and other conduits in basement 1-inch diameter 
and larger are run exposed on basement ceiling and are installed 
parallel to the lines of the building. As a general rule, all other 
conduits in the building (except in roof space and in unfinished 
attics) are concealed. 

Conduits in floors are run in the most direct manner and are 
not usually made larger than 1^-inch diameter, a larger size be- 
ing difficult to conceal in floor construction. 

Care is taken that conduits do not cross each other in the 
floor construction in such manner as to occupy more than 3 inches 
total space. 

In most cases the conduits run up from the cabinets and run in 
floor construction above with drops to the single-pole snap 
switches at entrance doors. This is, however, governed by the 
construction, ceiling heights, etc., and an effort is made to re- 
duce the length of the runs to a minimum. 

The following tables are used to ascertain the sizes of conduits 
to accommodate the various sizes and numbers of wire : 



CONDUIT SIZES FOR CONDUCTORS 



WIRE AND CABLE SIZE 

fB. & S. GAUGE) 


TWO 

WIRES 

SAME SIZE 


THREE 

WIRES 

SAME SIZE 


FOUR 

WIRES 

SAME SIZE 


THREE 

WIRES 

DOUBLE 

SIZE 
NEUTRAL 


DUPLEX 

WIRES 


14 


inches 

l 

2 
3 

4 
3 
4 

1 

1 

u 

li 
li 

n 

l* 

2 
2 
2 
2\ 

2i 

2| 


inches 

3 

4 
3 

4 

1 
1 
li 

li 

H 

H 

2 

2 

2 

2 

2h 
2| 

3 


inches 

3 
4 
3 
4 

1 
1 

li 
li 
H 
li 

2 

2 

2 

21 

2| 

2* 

21 

■a 2 

3 
3 


inches 

3 

4 
3 

4 

1 
1 

li 
li 
l* 
H 

2 

2 

2* 

2| 

2* 


inches 
l 


12 


l 


10 


3. 


8 




6 




5 




4 




3 




2 




1 









00 




000 




0000 




200,000 




250,000 




300.000 









200 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



The above table is based on single-conductor double-braided 
rubber-insulated wire and unlined metal conduit. All wires 
No. 8 and larger are stranded. 

The conduit sizes are given for runs up to 100 feet with not 
more than four right-angle bends between outlets. For longer 
runs larger conduits are used. 



LEAD ENCASED CABLE IN UNLINED METALLIC CONDUIT 



WIRE AND CABLE SIZE 
(B. & S. GAUGE, 



8 

6 

5 

4 

3 

2 

1 



00 

000.... 
0000... 
250,000 
300,000 



TWO WIRES 
SAME SIZE 



inches 

n 
i* 

2 
2 
2 
2 
2 

2| 
2* 



THREE WIRES 
SAME SIZE 



inches 
1* 

2 

2 

2 

2 

91 
L i 

^2 
^2 

3 
3 
3 
3 

3* 



FOUR WIRES 
SAME SIZE 



inches 

n 

2 
2 
2* 

2| 

^2 

3 

3 

3 

3 

3 

3^ 

3| 



THREE WIRES 

DOUBLE SIZE 

NEUTRAL 



inches 

11 

2 
2 
91 

^2 

2| 

2£ 

3 

3 

3 

3 



OUTLETS 



The standard types of stamped steel outlet boxes suitable for 
rigid conduits are used. No conduit larger than J inch is con- 
nected to any outlet box, and not more than four connections 
are made to any outlet box. 

Outlets are located with reference to the architectural treat- 
ment and the construction of a building. This generally requires 
symmetrical spacing. 

Ceiling outlets are used for general illumination, and bracket 
outlets only where space restrictions demand, i.e., small toilet- 
rooms, stair landings, low ceilings, etc. 

As a general rule, ceiling outlets in the same space supply from 
100 to 300 square feet of floor area. 



CONDUIT AND WIRING SYSTEMS 201 

In general, the capacity of a ceiling outlet does not exceed 300 
watts; a bracket outlet, 50 watts; a receptacle, 50 watts. Bracket 
outlets in court rooms, in lobbies, on exterior of building, etc., 
may supply 100 or more watts. Court-room and lobby ceiling 
outlets, where the total number of outlets is restricted by the 
architectural treatment may have a greater capacity than 300 
watts, and such outlets sometimes require more than one circuit. 

Rooms less than 20 feet square have one ceiling outlet. Rooms 
over 20 feet in either dimension have two or more ceiling outlets 
placed on the longer dimensions, the number of rows of outlets 
being governed by the width of the room. 

In the post-office workroom, a space about 3 feet adjacent to 
the screen is considered to be sufficiently lighted by the brackets 
on the screen, and this area is deducted from the total area of 
the room when calculating the illumination. 

In locating outlets in large office rooms consideration is given 
to the possibility of such rooms being subdivided at some future 
time. 

The location of ceiling outlets in court rooms and in main lob- 
bies depends very largely upon the design of the ceilings and other 
architectural features of these spaces. 

Ceiling outlets are located in the centers of squares whenever 
practicable. 

It is considered that approximately uniform illumination is ob- 
tained when the distance between the outlets is equal to twice 
the height of the lamps above the plane of illumination, using re- 
flectors which direct the greatest portion of the light downward 
within an angle of 60° from the vertical and with the maximum 
apparent candle-power at about 45° from the vertical. 

Outlets near beams are located a sufficient distance from the 
beam to admit of placing a standard 4-inch outlet box, and if the 
beams project below the ceiling the outlet is located a minimum 
of 12 inches from 'the center of beam. If a beam is directly over 
a necessary or very desirable location for an outlet, an effort is 
made to have the structural engineers substitute two channels 
with a lj-inch space between the same for the single beam. 

Outlets are not placed within 6 inches of heating mains or other 
large piping. 

Ceiling outlets are not placed on skylight frames unless this is 



202 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

absolutely necessary, and then the architectural draftsman is 
called upon to give special construction of the frames to accom- 
modate the conduit and gas piping, outlet boxes, canopies, etc. 

Combination ceiling outlets are not used where ceiling heights 
are less than 8 feet 6 inches. 

The standard height of bracket outlets is 7 feet above the floor, 
but they are frquently placed higher in court rooms. 

Bracket outlets are located so that the fixture canopy will seat 
on a smooth plane surface not less than 5 J inches wide. 

Bracket outlets are provided over each window in the post- 
office screen. Bracket outlets are provided on the lock-box sec- 
tion also, on the basis of one outlet for each 4 to 6 feet of length 
of the box section. 

To supply the local illumination of furniture in the post-office 
workroom, junction boxes with closed covers are set out fully 
exposed on the basement ceiling. One box is provided for each 
300 square feet of floor area, and each box is rated at 300 watts 
in calculation of wire sizes. 

Receptacle outlets for local illumination are placed in walls of 
all office rooms, and also in floors of the principal offices. 

The floor outlets are located on center lines of rooms, longer 
dimension, and one floor outlet is provided for each 250 square 
feet of floor area when more than one such outlet is needed. 

Desks are generally placed so as to receive a maximum amount 
of daylight, and this guides the selection of the locations for wall 
outlets which are generally located in exterior walls. One such 
outlet for each window of the average office is provided unless 
conditions indicate the need of a greater number. Money order 
and registry rooms have two or more wall outlets. 

An outlet is provided in each elevator and lift shaft, and located 
near center of travel of car. 

A plug receptacle is provided in the floor under each end of the 
judge's bench. A plug receptacle is also provided for the clerk's 
desk. 

Combination bracket outlets are provided over the wall writing 
desks in public lobby. These outlets provide gas burners for 
emergency lighting, as combination ceiling fixtures are rarely 
installed in lobbies or corridors. Gas only or combination brack- 
ets are also installed in basement and in corridors on upper floors 
for emergency use. 



CONDUIT AND WIRING SYSTEMS 203 

Outlets on portable lobby desks are so connected that tearing 
up of floor to place conduit will not be necessary; a junction box 
is set on basement ceiling near probable location of riser to desk 
bracket, and the horizontal run of conduit from box to desk riser 
is exposed on basement ceiling. 

The outlet for the elevator circuit is generally connected on a 
basement circuit which supplies outlets in boiler room. 

The special junction boxes on the basement ceiling are con- 
nected two on a circuit; or, in case of an odd number, one or 
three per circuit. 

Branch circuits are connected so that the loads on the two 
sides of the 3-wire circuit will be approximately balanced. 

Outlets in public toilets and in attics are connected on corridor 
circuits. 

Independent circuits are provided for post-office screen outlets. 

Lobby outlets, outside entrance outlets, and basement out- 
lets not in spaces connected with post-office working space are 
connected to a tablet in basement or in the smaller buildings to 
the workroom tablet. 

The outlets for lobby desks are connected to either the work- 
room or basement tablets. 

In court rooms an independent circuit is provided for the out- 
lets at the judge's and clerk's desks, and if conditions require 
two circuits are provided to each ceiling outlet. 

Outside fixtures at each entrance are usually connected on a 
separate circuit, but where the fixtures are small those at two 
entrances are connected on one circuit, each entrance being con- 
trolled by a snap-switch. 

Lead-covered, rubber insulated wire is run from junction boxes 
just inside wall in basement to outdoor lights at main entrances. 

A plug receptacle is provided on exterior of each vault in the 
building, near lock side of door; and if the vault exceeds 80 square 
feet in floor area a ceiling outlet box is provided in vault with a 
receptacle just inside of vault door, so that the inner and outer 
receptacles may be connected with a flexible cord when desired. 

Outlets are located in the roof space or attic, as judgment dic- 
tates. Ample illumination is provided for the overhead sheaves 
of elevators. 

Outlets for ceiling fans, allowing one outlet for each 600 to 800 
square feet of floor space, are provided for the post office work- 



204 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

room. These outlets are connected two or three on a circuit to the 
workroom tablets. Ceiling fan outlets are never connected on 
the same circuit with lights. 

Each branch circuit is controlled by a double-pole fused knife- 
switch located on the distributing tablet. 

Except for the post-office workroom and general basement and 
unfinished attic or roof spaces, all ceiling outlets and all bracket 
outlets are controlled by snap-switches. Snap-switches are single- 
pole push-button flush type, and are set 4 feet above the floor; 
and those in public lobby have lock attachment. 

Snap-switches in rooms are located near the entrance door cas- 
ing on the lock side. Large rooms which have two entrance doors 
from corridor and more than one ceiling outlet have a snap-switch 
at each entrance door. Switches controlling large spaces and 
long corridors are frequently placed in gang boxes. Switches are 
not located in partition walls less than 4 inches thick, and are so 
placed that the face plate will seat on a smooth plane surface. 

A uniform size 10-ampere fuse is used for all branch circuits. 
The smallest wire used in branch circuits is No. 12, and in lighting 
fixtures the smallest wire used is No. 16 B. and S. gauge. The 
sizes of fuses for feeders and sub-feeders are selected to corre- 
spond to the carrying capacity of the wires which the fuses pro- 
tect. In case of a small switch controlling a large cable the size 
of the fuse is adapted to give protection to the switch. 

GENERAL ILLUMINATION 

In computing the number of watts required for a certain area 
the well-known formula recommended by the National Electric 
Lamp Association may be used: 

TTT ^ Floor area in square feet X foot candles 

Watts = — - — r-^-j . 

Effective lumens per watt 

It is convenient to solve directly for the number of lamps for 
a given area; so the following formula is used: 

pj Area in square feet X lumens per square foot 

Lumens per lamp 



CONDUIT AND WIRING SYSTEMS 



205 



The lumens per lamp used are those given by the various 
lamp manufacturers. 

The lumens per square foot for general illumination, using 
direct lighting for the several classes of rooms are as follows : 



CHARACTER OF SPACE 



Boiler, Store and Machinery Rooms 

Toilets, Halls, ' Corridors, Vesti- 
bules, etc 

P. O. Workroom 

Money Order and Registry Rooms. . 

Main Lobby and Main Stairs 

Civil Service Rooms 

Office Rooms 

Court Rooms 

Swing Rooms and Jury Rooms 



LUMENS PER SQ. FT. 
NEW BUILDINGS 



Outlets spaced 
14 ft. on centers 

3.0 
7.5 and special 
7.5 and special 

6.0 

7.5 
7.5 and special 

7.5 

5.0 



LUMENS PER SQ. FT. 
OLD BUILDINGS 



14 ft. centers 



3.0 

10.0 and special 
10.0 and special 
6.0 
10.0 
10.0 and special 
10.0 
5.0 



The plane of illumination is taken as 2 feet 6 inches above floor in all 
cases. 

For indirect and semi-indirect lighting the values given for new building 
should be doubled. 

The following table gives the effective lumens per watt for 
the lamps and reflectors used: 

Lamps Walls L 

Tungsten (vacuum) Light 5.0 

Tungsten (vacuum) Dark 4.2 

Gem Light 2.0 

Arc lamps Large areas 3.0 

Tungsten (gas filled) ....Light 6.0 to 9.0 

The above values apply to small and medium size rooms. 
Very large rooms are given special consideration. 



WIEING 

The standard wiring for lighting in all buildings is 3-wire feed- 
ers, 3-wire sub-feeders, and 2- wire branch circuits. This may be 
varied to suit local conditions, as in a 4-wire distribution system 
the four wires will be brought to main feeder tablet or switchboard 
and 3-wire feeders run from this point to distributing cabinets. 



206 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

The even-number wire sizes are used for feeders and sub-feeders 
smaller than No. 5. 

In the smaller buildings the fewest possible numbers of wire 
sizes for feeders is used. 

All branch lighting circuits are No. 12 B and S., except circuits 
to the special junction boxes on basement ceiling for furniture 
lighting, which are made No. 10 B. and S. 

The maximum allowance for branch circuits is 800 watts ex- 
cept in post-office workroom where the maximum is 660 watts. 

All lighting feeders and sub-feeders (or mains) are calculated 
on the following basis: 

The assumed lighting load is the total watts for general illumi- 
nation plus the total watts for local illumination (50 watts per 
receptacle) plus one watt per square foot of post-office work- 
room floor space. 

Load factors for small buildings, one to one and a half stories. 

Feeders Full connected load 

Sub-feeders Full connected load 

Load factors for buildings containing more than four distributing 
tablets. 

Feeders 70 per cent of connected load 

Sub-feeders 80 per cent of connected load 

Sub-feeders to workroom and court-room tablets are calcu- 
lated for full load in all cases. 
Voltage drop. 

per cent 

Feeders 3 

Sub-feeders 2 

Branch circuits 1 

Feeders and sub-feeders for all buildings containing not more 
than three distributing tablets are calculated on the basis of 2- 
wire circuits and 110 volts. The wire size given by formula is 
the neutral, and each outside wire is one-half the neutral size, 
so that the systems may be used either for 2-wire or 3-wire service. 
No feeder or sub-feeder neutral wire is less than No. 8 B. and S, 
or larger than 300,000 cm. 



CONDUIT AND WIRING SYSTEMS 207 

Where a building contains more than three distributing tab- 
lets and the supply system is the usual 110-220 volt 3-wire system, 
a straight 3-wire system 110-220 volts is used up to the distribu- 
ing cabinets. The wires are calculated for outside volts, and the 
neutral wire is made the same size as one of the outside wires. 
The feeders and sub-feeders are calculated for full-connected load, 
and with 2 per cent drop in sub-feeders and 3 per cent drop in 
main feeder. 

The three wires of a 3-phase circuit and the four wires of a 2- 
phase circuit are all made of the same size, and each conductor 
is of the cross-section given by the formula hereinafter stated. 

Branch circuits to single arc lamps are increased 50 per cent to 
provide for the extra current at starting. 

The carrying capacity of all feeders and sub-feeders at the load 
factors given is not to be less than hereinafter stated, regardless 
of the voltage drop. This requirement will generally determine 
the wire size, but in all cases the voltage drop on feeders and sub- 
feeders is calculated. As a rule, the drop is less than the allowed 
maximum in sub-feeders 60 feet long and under, and in main 
feeders 100 feet long and under. 

WIRING FORMULAE AND TABLES 

Feeder and fuse sizes for direct current motors are calculated 
for a current of one and one-half times the full load running 
current of the motor and the wire size is selected from table A. 
(Page 210.) 

For alternating current motors feeder and fuse sizes for motors 
under 5 horse power are figured at three times the full load cur- 
rent and for motors 5 horse power and over at twice the full load 
current and wire size is selected from table B. (Page 210.) 

Current for single phase motors 



Horse power X 746 
Volts X power factor X efficiency' 



Current for two phase motors is one-half the above and for 3 
phase motors .58 times the above. 

The product of the efficiency and power factor may be taken 
as follows : 



208 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



orse power 
of motor 


Efficiency 
power factor 


1 


0.30 


2 


0.34 


3 


0.38 


4 


0.42 


5 


0.46 


7i 

• 2 


0.50 


10 


0.55 


15 


0.60 


20 


0.65 


25 


0.70 


30 


0.70 



If the feeder is more than 100 feet long a larger size should be 
used to keep the drop within the 2 per cent allowance for sub- 
feeders. 

The formula used when calculating direct-current work is as 
follows : 

cm = D x y 2L6 ; 

For single phase alternating current circuits where all wires 
are in same conduit: 

CM = D * 7 *f 6 . 
V X P. F. 

D = distance one way in feet. 
I = line current in amperes at lamp voltage. 
V = actual volts drop in transmission. 
P.F. = power factor. 

When this formula is applied, it will give the size of conductor 
for a 2- wire transmission. If the 3-wire system with the double 
neutral is desired then this gives the size of the neutral conductor, 
and each outside is to be made approximately one-half the size 
of the neutral. 

If the Edison 3-wire system (all conductors of the same size) 
is desired, then the same formula is applied with the following 
changes : 



I 



CONDUIT AND WIRING SYSTEMS 209 

I = total watts divided by twice the lamp voltage, or 
I = the current in either of the outside conductors of the 

Edison 3-wire system. 
V = twice the actual volts drop if the power is transmitted 

by a 2- wire system. 

These different calculations are based upon the same percentage 
loss of voltage in transmitting the power. 

In direct-current circuits the volts drop per wire = IR, and 
the total volts drop = 21 R. I is the current per wire, and R is 
the resistance in ohms per wire. 

In alternating-current circuits the volts drop depends on both 
the resistance and reactance but with wires close together as in 
conduit work the reactance will generally be small and may be 
neglected. However, for all alternating-current circuits the ac- 
tual volts drop may be calculated at the assumed power factor, 
load, and corresponding current, using the following formula: 

Volts drop per wire = IR -f- P.F. 

Volts drop, single-phase circuit = 2 (volts drop per wire) . 
Volts drop, 2-phase circuit = 2 (volts drop per wire). 

Volts drop, 3-phase circuit = 1.73 (volts drop per wire). 

In direct-current circuits the volts loss in per cent is the same 
as the per cent power loss. This is not the case in alternating- 
current circuits except at unity power factor. 

A convenient method of determining wire sizes is to ascertain 
first the current per wire and select a wire size which has this 
capacity; then calculate the volts drop for the wire thus selected. 

POWER FACTORS — LIGHT AND POWER 

per cent 

Incandescent lamps 95 

Arc lamps 70 

Incandescent lamps and induction motors 85 

Induction motors, full load 80 

Induction motors, constant speed type, starting 60 

Induction motors, elevator type, starting 70 

The power factor of an unbalanced 3-phase circuit is obtained 
from the following formula: 



210 



MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 



Power factor, three phase, — 



Total real watts 



Volts across lines X average 
amperes per phase X 1.73 



WIRE AND CABLE DATA— CONDUIT WORK 



SIZE, B. AND S. 



14.. 
12.. 
10.. 
8... 
6... 
5... 
4... 
3... 
2... 
1... 
0... 
00.. 
000. 
0000 



SIZE, CIRCULAB 
MILS 



4,107 

6,530 

10,380 

16,510 

26,250 

33,100 

41,470 

52,630 

66,370 

83,690 

105,500 

133,100 

167,800 

211,600 

250,000 

300,000 



SAFE CABBYING CAPACITY 
IN AMPEBES 



15 

20 

25 

35 

50 

55 

70 

80 

90 

100 

125 

150 

175 

225 

250 

275 



B 



20 

25 

30 

50 

70 

80 

90 

100 

125 

150 

200 

225 

275 

325 

350 

400 



BESISTANCE, 
OHMS PEB 1,000 
FEET AT 68° F. 



2.5200 
1.5900 
0.9970 
0.6270 
0.3940 
0.3130 
0.2480 
0.1970 
0.1560 
0.1240 
0.0981 
0.0778 
0.0617 
0.0489 
0.0414 
0.0345 



The preceding is used for both interior and underground cir- 
cuits, and for all kinds of insulation. Column "A" is always 
used except for alternating current motors, when column U B" 
is used. 

Switchboards. In designing switchboards an attempt is made 
to keep the size of the panels as closely to standards adopted by 
the various manufacturers as possible. 

The majority of switchboard manufacturers make their panels 
20 inches, 50 inches, and 70 inches high, and the widths of panels 
are made 16 inches, 20 inches, 24 inches, 32 inches, and 36 inches. 
The thicknesses are lj inches, 2 inches, and 3 inches. 

The specifications usually state that the switchboards shall not 
be less than 62 inches nor more than 70 inches high and that 
panels must not be less than 24 inches nor more than 32 inches 
wide, and the thickness not less than 1| inches nor more than 2 
inches. 



CONDUIT AND WIRING SYSTEMS 211 

ESTIMATING DATA 

The average total cost of lighting systems for new buildings, 
complete in place, can be figured at about $12 per outlet in 
eastern sections of the country, $15 in the west and south, 
and $20 in the extreme west. Conduit and wire in place 
will average about 12 cents per foot for all sizes. This includes 
outlet boxes, but does not include, switches, receptacles, cabinets 
and tablets, etc. 

These figures are based only on the number of actual lighting 
outlets, switch outlets not being included. 

For old buildings the cost of the work will be about $25 per 
outlet in the extreme west, and from $20 to $25 per outlet in 
other sections. 

Estimating in detail. The total amounts of conduit and wire 
are the lengths scaled on the plan plus the following: 

Number of ceiling outlets x 2 feet. 
Number of bracket outlets x 10 feet. 
Number of switch outlets x 10 feet. 
Number of baseboard outlets x 4 feet. 
Number of 2-gang switches x 15 feet. 
Number of 3 -gang switches x 20 feet. 

The average length of branch runs in Federal buildings is 50 
feet. 

Branch conduits \ inch; branch circuits in Federal buildings 
are No. 12 B. and S. duplex wire. 

For obtaining lengths of feeders make a diagram of all feeder 
and sub-feeder circuits. 

Materials. 

Conduit in place in new building, per 100 feet. 



\ inch $7 .00 

f inch 9.00 

1 inch 13 .30 

11 inch 18 .00 

1$ inch 21 .50 

2 inch 29 .00 

2\ inch 45.60 

3 inch .* 60 .00 



212 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Add 50 per cent to above for underground service connections 
in place and for work in old buildings where walls and ceilings are 
cut and plaster must be replaced. 

Conduit elbows in place, each: 

2 inch $1 .00 

2\ inch 1 .25 

3 inch 4.00 

4 inch 10 .00 

Outlet boxes in place, all kinds, each: 

In new buildings 0.25 

In old buildings where plaster must be repaired 0.50 

Large junction boxes, per pound, in place 0.05 

Plug receptacles in place, each 1 .90 

Snap switches (single-pole 10-ampere), in place, each 1 .40 

Fixture studs, each, in place .05 

Double braided rubber-insulated wire, in place per 1000 
feet: 16 cent base 

Solid single conductor: 
Size, B. & S: 

16 15.00 

14 18 .60 

12 23.40 

10 30.40 

Size, CM. : 

250,000 460.00 

300,000 530.00 

400,000 670 .00 

500,000 814.00 

Stranded single conductor: 

8 47.40 

6 70.00 

4 95.50 

3 113.00 

2 132.00 

1 172.50 

210.00 

00 250.00 

000 300.00 

0000 '. 362 . 00 



CONDUIT AND WIRING SYSTEMS 213 

Duplex conductors: 

14 $36.00 

12 45 .70 

10 60.00 

8 . 79.50 

Telephone cabinets, special office design, in place, each. . . 20.00 

Outlet bushings, each, in place .05 

Lock nuts, each in place .01 

(Estimate three bushings and three lock nuts per outlet.) 
Reinforced silk-covered lamp cord, No. 16, per 1000 feet, 

jl in place 55 .00 

Knife switches, 250-volt, single-break, with extension for 
fuses unmounted, polished: 

Capacity Double-pole Triple-pole 

30 1.40 1.90 

60 1.80 2.75 

100 3.50 5.25 

200 5.40 8.15 

400 12.20 18.60 

600 17.15 26.00 

800 28.00 42.00 

1000 32.20 48.50 

1200 38.00 57.50 

Cost of mounting, not including drilling of marble, per 
switch $1 .00 to $10.00 

Enclosed fuses in place, each: 

3 to 30 amperes . 16 

35 to 60 amperes. , .22 

65 to 100 amperes .57 

110 to 200 amperes 1 .25 

225 to 400 amperes 2 .30 

450 to 600 amperes 3 .50 

Bus-bars for switchboards, per pound, in place 0.50 

Structural steel work for switchboards, per pound, in place. 0.10 

Blue Vermont marble, 2-inch thick, per square foot 2 .00 

Slate panels, l|-ingh thick, per square foot 0.50 

Drilling holes, slate and marble, each .25 

Labor on switchboard panels, each: 

In shop 25 .00 

At building 12 .00 

Total $37 .00 



214 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Tablets and cabinets (office special design), per switch $5.00 

To actual cost of tablets, if ascertainable, add for installa- 
tion, per circuit 1 .00 

Motor connections, 5-H.P. and under, per H.P 2 .00 

Motor connections, from 10-H.P. up, per H.P 1 .00 

Railroad fare on average Federal building 50.00 

Board per man, per day 1 .00 

Freight, 3 per cent of total cost of material and labor. 
Superintendence, 1 per cent of total cost of materials and labor 
Profit, 20 per cent of total cost of materials and labor. 

Especial attention is called to the fact that the foregoing figures 
are correct for certain special conditions in new Federal buildings, 
but are not applicable under all conditions. Used with judgment 
they give accurate results. 

CONDUIT SYSTEMS FOR TIME CLOCKS AND OTHER SPECIAL PURPOSES 

The office has discontinued the installation of standard clock 
systems except in special cases. In the larger buildings, how- 
ever, where a conduit system for signal wires is installed, these 
conduits could be used for clock wires, if desired. 

The standard time clock systems formerly installed in Federal 
buildings under control of the Treasury Department, consisted 
of a master clock operating, by means of electricity or air pressure, 
secondary clocks located throughout the building. The sec- 
ondary clocks contained no driving mechanism proper, being 
driven solely by impulses from the master clock, and did not re- 
quire winding, oiling, or setting. 

The master clocks for the pneumatic systems were either self- 
contained or used a water-operated compressor which automati- 
cally maintained a constant pressure in a storage tank. The master 
clock operated a valve once each minute, thus forcing air to travel 
through the piping and operate the secondaries. 

In the electric systems, the secondary clocks were provided 
with electro-magnets connected in series. The master clock was 
provided with a circuit-closer which automatically closed the cir- 
cuit (or relay) once each minute. The magnets in the secondaries 
were thus energized, and the armature which was attracted moved 
the hands forward one minute. 



CONDUIT AND WIRING SYSTEMS 215 

The secondary clock circuits for the electric system, if not 
more than three, were supplied through relays located in the 
master clock. Each circuit was fitted with a small telltale clock 
mounted in the master clock. 

Buildings with twenty or more office rooms (including post-office 
workroom, money-order room, and lobby), were provided with a 
complete conduit system for clocks. 

Not more than twenty-five secondary clocks were installed on 
one circuit, and the circuit began and ended at the master clock. 
In buildings where there were more than twenty-five secondaries 
they were grouped on different closed circuits, with not more 
than twenty clocks on a circuit. The various circuits contained, 
where practicable, the same number of clocks, and each circuit 
was connected with the master clock outlet, which was connected 
to the junction box in the vault protection service conduit just 
inside of basement wall to permit connections at this point to the 
battery, or to the lines of the telegraph companies for synchro- 
nizing the clocks. 

All conduit systems were f-inch diameter, and the clock outlet 
boxes were of special design. The conduits were arranged for 
the pulling in of wires, or of lead tubes for the pneumatic system. 

The master clocks were of the wall type and were located in 
the post-office workroom in such position as to be visible from all 
parts of the room, care being taken that near-by columns, sus- 
pended lookouts, etc., did not obstruct the view. Master clock 
cases varied in size from 64 inches to 90 inches in height and from 
20 inches to 24 inches in width. 

A secondary clock was located in each office room throughout 
the building, in the carriers' swing room, the money-order and reg- 
istery division, and the court room. 

The clocks in office rooms were installed over doors if ceiling 
heights permitted. In rooms which were long in proportion to 
their width, the clocks were located on an end wall in preference 
to a side wall. In extremely long rooms a clock was placed at 
each end of the room. Clocks in court rooms were placed so as 
to be easily seen from the judge's desk. 

The weight of the average size electric and pneumatic second- 
ary clock used was 4 pounds. For ordinary office rooms where 
the distance from the clock to any point in the room did not ex- 



216 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

ceed 40 feet, clocks with 12-inch-diameter dials were installed. 
Where the distance was greater, 2 inches were added to the di- 
ameter of the dial for each additional 10 feet. The standard sec- 
ondary clock with 12-inch dial was 17 inches x 17 inches outside 
dimensions. 

In court rooms and rooms over 14 feet high, the size of the clock 
dial was determined as above when the clock was to be set 10 feet 
above the floor. For greater heights above floor, the diameter 
of the dial was increased approximately 12 inches for each addi- 
tional 10 feet. The architectural treatment of the walls received 
consideration in deciding upon the size of the clock dial. 

The clocks usually had a 12-inch dial, Arabic numerals, and an 
oak case. 

TOWER CLOCKS 

Three types of tower clocks are in use on Federal buildings; 
mechanical, electrical, and pneumatic. 

The mechanical tower clocks used have generally the ordinary 
clock mechanism operated by weights, wound up by hand once 
a week. This is the cheapest form of clock, and is reliable. The 
present practice is to require that the mechanical clock weights 
be automatically wound by means of a motor operated on the 
lighting circuit or by storage batteries. All clocks are provided 
with a pilot clock so that the hands may be set from the clock 
room, and the pilot clock is provided with a second-hand. In 
order to equalize the cost of the mechanical clock with the other 
two systems, a clock is placed in some part of the building and 
operated electrically as a secondary from the tower clock. 

All types of tower clocks used are provided with a device for 
automatically switching on and off the lighting system installed 
for illuminating the clock dial or dials; and all are guaranteed to 
vary not more than thirty seconds per month. 

The pneumatic system consists of a hydraulic air compressor 
and galvanized steel air storage tank, with a master clock located 
in some part of the building, from which the tower clock is oper- 
ated as a secondary. 

If a building is equipped with an electric clock system the 
tower clock is operated as a secondary from the master clock, the 
same as any other secondary. 



CONDUIT AND WIRING SYSTEMS 217 

If a building has no clock system, a master clock is installed in 
the post-office workroom or custodian's office, and the tower 
clock is operated therefrom as a secondary. The hands of the 
electric tower clock are operated by a small motor controlled by 
the master clock, and this motor is wound for 20 to 25 volts and 
operated by 40 wet cells, which will run the motor one year. 

The tower clock mechanism occupies a space about 24 inches 
x 24 inches in plan, and for the electric system the mimimum dis- 
tance from the center of the clock dial to the stand for supporting 
the mechanism is not less than 24 inches. The electric clock 
mechanism weights about fifty pounds, and is, when possible, 
located in a room protected from the weather; otherwise it is 
installed in a glass case. 

In the event a bell and striking mechanism is desired in con- 
nection with a tower clock, it is located in a room above or below 
the clock mechanism, or in same room if necessary. The striking 
mechanism weights about forty pounds. 

The room for the bell has large openings extending from floor 
to ceiling to permit the egress of sound. If louvres are used they 
are widely spaced and backed up with wire grills. 

A bell room 6 feet x 6 feet in plan and 7 feet to 8 feet high is 
the standard size. The bell room is made not less than 10 feet 
higher than the roof of the building. 

The floor and ceiling of the bell room have mineral wool deaden- 
ing between joists if wood construction is used. 

The space occupied by the bell and its supporting stand is ap- 
proximately 6 feet x 6 feet in plan for a 2000-pound bell. On ac- 
count of hills, street noises, etc., no definite rule can be laid down 
as to how far a bell can be heard, but under ordinary conditions 
a 1400-pound bell can be heard one mile, and a 2000-pound bell 
two miles. 

In small Federal buildings a 1400-pound bell is installed, and in 
the larger buildings a 2000-pound bell. Chimes or peals are not 
used. 

The clock dials are made 3 feet diameter for towers up to 30 
feet high. For each additional 10 feet one foot is added to the 
diameter of the dial. 

The tower clock hands are made of aluminum. 

If a bell is installed with a tower clock, and no other secondary 



218 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

clocks are used in the building, the wet batteries for the clock 
motor can not be used, as the striking mechanism takes too much 
current; therefore a storage battery is installed, which is charged 
from the lighting or power service of the building. If only al- 
ternating current is available, a rectifier is used and a charging 
tablet is installed, on which is mounted a double-throw switch, 
voltmeter, ammeter, reverse current relay, and a bank of resist- 
ance lamps for charging the storage batteries, consisting of 12 
cells each, rated at 4 amperes for eight hours. 

The proper illumination of tower clock dials is difficult to ar- 
rive at, and generally expensive to maintain. The office has 
abandoned its former practice of placing a ring of lights about 2 
feet back of each clock face, as a dark spot will appear on the 
dial if one light goes out, and the dial will have a spotted effect 
even with all lights burning. It is better to drop down from the 
center of the ceiling of clock room with a conduit and place a 
ring made up of conduit and condulets, or regular boxes with re- 
ceptacles, to form a large cluster, and install 40-watt or larger 
tungsten lamps, with x-ray reflectors.^ An abundance of light is 
necessary, approximately 15 candle-feet on the dial being required. 

The walls and ceiling of the clock room are given three coats 
of lead and oil or white enamel paint to increase the reflection. 

A good way to illuminate clock dials where room is small is 
to treat the walls of clock room as noted above and drop two 
large tungsten lamps in center of room, same to be on separate 
circuits and each large enough for excellent illumination of dial. 

ESTIMATES OF COST OF STANDARD TIME CLOCK SYSTEMS 

Cost per cell (new) $1 .50 to $2 .00 

Voltage per cell 0.6 to 0.7 volts 

Life of cell, approximately 300 ampere hours 

Length of contact made by master clock § second 

Voltage required per secondary clock, approxi- 
mately H volts 

Amperes required per circuit 1 ampere 

The number of cells required for operating electric secondaries 
is equal to twice the largest number of clocks on any one circuit. 

For preliminary estimates it is sufficiently accurate to allow 
about $25 per secondary clock and add $200 for the master clock. 



CONDUIT AND WIRING SYSTEMS 219 

Of the $25 per clock, $15 may be taken for the clock and wiring and 
$10 for the conduit system. This will give about the lowest cost, 
and the estimate should be increased from 10 to 20 per cent in 
remote cities. 

One thousand feet of J-inch conduit in place costs approximately 
$70 in new buildings, and $200 in old buildings where cutting is 
needed and plaster must be patched. One thousand feet of No. 
16 wire in place costs approximately $15. 

The outlet boxes now used in Federal buildings cost about 25 
cents each in place in new buildings, and 50 cents in old buildings. 

The cost of hanging and connecting an electric secondary clock 
is about $1.50. Connections are made into top of clocks. 

The cost of an average electric tower clock with no other sec- 
ondaries, including dial, hands, mechanism, batteries, master 
clock, etc., complete may be taken at about $1250. This does 
not include cutting for clock dials, or other structural work. 

The mechanically operated tower clocks will average about 
$1000. 

For striking mechanism, including 2000-pound bell, add $1200. 
Bells will average 50 to 60 cents per pound at factory. 

FIEE ALARM AND WATCHMAN^ TIME-DETECTOR SYSTEM 

In buildings with fifty or more office rooms, a conduit system 
for fire-alarm apparatus and a conduit system for watchman's 
time-detector are installed. 

For the fire-alarm system two outlet boxes, one above the other, 
are provided at each station ; the lower being about 60 inches above 
the floor and the upper one 2 feet below ceiling. These boxes are 
located at various appropriate points in the corridors and else- 
where, and are joined in series by 1-inch conduit. The conduit- 
system begins and ends at a large junction box in the engine 
room. From this junction box a conduit is run to the place where 
the batteries are to be located. For convenience, the boxes on 
the several floors are located in vertical rows, and a single riser is 
run through all the boxes in that vertical row. These risers are 
cross-connected in the basement. 

The upper outlet used on the fire-alarm system is similar to the 
regular switch outlet box, or the regular ceiling outlet box with 



220 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

brass cover with a bushed opening for connection to a gong. The 
lower box is 12 inches wide by 17 inches high by 6 inches deep, clear 
inside, made of steel with a steel cover flush with plaster line and 
secured to the box with tap screws. 

Outlet boxes for the watchman's time-detector system are lo- 
cated in remote corners of the public portions of the building, pre- 
ferably in vertical rows, and connected by 1-inch conduit similar 
to the fire-alarm boxes. These risers are run to a common junc- 
tion box located in the office of the assistant custodian, and from 
said box a 1-inch conduit is run to the place where batteries are 
located. 

Watchman's clock and fire-alarm systems use No. 16 and No. 
18 wire. There is one more wire in the conduit than there are 
stations on the line. The watchman's boxes are 5 inches wide by 
8 inches high by 6 inches deep, clear inside, and made of steel 
with a steel cover set flush with plaster line and secured with 
tap screws. 

The cost of these systems will average $10 per outlet. 

VAULT-PROTECTION SYSTEM 

All Federal buildings are provided with a conduit system for 
the reception of the wires of an electric vault-protection system. 

The wiring for each vault consists of a cable which leads to a 
common junction box for all vaults, which is located in the base- 
ment. From this junction box a. conduit, never less than 1\ 
inch diameter, is run underground to the service pole and up in- 
side of same to the top. A f-inch conduit is also taken from this 
junction box and run to a point selected for alarm gong near ceil- 
ing of the post-office workroom. 

From the junction box in basement a f-inch diameter conduit 
is run to each vault in the building with a steel outlet box located 
near door trim on the exterior of the vault about 4 feet 6 inches 
above the floor, and a box is located near the ceiling on the inside 
of the vault near entrance door. 

The size of the main service conduit from the junction box to 
the pole is such that the 4-pair cables from each vault when 
grouped and formed into a cable will not fill more than two-thirds 
of the conduit. 



CONDUIT AND WIRING SYSTEMS 221 

In the larger buildings the vault protection main service con- 
duit is used to bring in the telegraph wires for the Weather Bureau 
service and also the clock and messenger call-bell wires from the 
telegraph companies. 

The entire cost of this system will average $20 per vault. The 
wiring in the conduits is supplied by the companies furnishing the 
service. 

TELEPHONE AND CALL BELL CONDUITS 

A conduit system for telephones and call bells is installed in all 
Federal buildings, and is so arranged that intercommunicating 
telephone systems may be installed if desired. 

As previously stated, in the small buildings the main service 
conduit for the vault protection service is used to bring in the 
main telephone wires to the junction box in basement. From this 
junction box in small buildings a 1-inch conduit is run to a tele- 
phone junction cabinet centrally located on first floor; and from 
the junction cabinet radiate separate J-inch diameter conduits to 
the various office rooms and stations. 

The standard size of telephone junction cabinet is 24 inches 
wide by 18 inches high and 3 inches deep, and it is constructed 
of sheet steel with a steel frame and hinged door with lock and 
key. 

The outlet boxes for telephones are steel, and are provided with 
a cover of brass for bushed hole in same. 

Small buildings are those in which the number of stations is 
less than 23. A large building has 23 or more stations, with 
provision for switchboard with operator. 

In the large buildings, if there is only one telephone company 
in the city, a main service conduit never less than l|-inch diame- 
ter is run from the building underground to the nearest pole of 
the telephone company, terminating 10 feet above grade with 
weatherhood. Where there are two companies two conduits are 
run, one to the pole of each company. 

Where a switchboard is to be installed the architect must ar- 
range for a room not less than 10 by 12 feet, with good natural 
light, located if possible on the first floor near to the cable termi- 
nal room in basement. 



222 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

The terminal room is arranged to receive all conduits from risers 
and from service poles. The telephone company will provide 
the terminal board, but the conduits should be arranged to per- 
mit the terminals being inclosed within a wooden cabinet. Ter- 
minal boards cover approximately, for each 100-pair cable distrib- 
uted, a space 9 inches wide and 4 feet long by 12 inches deep, 
but boards are usually arranged to be square for sizes less than 
100 pairs. The service conduit enters at the center at bottom, 
and all risers and conduits to switchboard room leave at the top 
of board. The riser conduits are not less than lj-inches, and 
switchboard conduit is 2 inches. The horizontal runs of riser 
conduits exposed on basement ceiling have a pull box after every 
two bends and at the foot of each vertical riser. Riser conduits 
enter the bottom of junction cabinets and leave at top to con- 
nect to the next above. All branch conduits from cabinets are 
J inch and leave at the bottom. No more than 20 conduits ars 
run from one cabinet. 

In office rooms an outlet box is installed in center of room. 
Where wood floors are specified, removable floor boards are pro- 
vided by the architect every 7 feet. These boards are without 
tongue, screwed to nailing strips, and have in the center of the 
under side, running lengthwise, a slot about f inch deep and f 
inch wide. These slots are connected to the floor box by a \ inch 
conduit having a bushed end under the board. This arrangement 
will permit reaching desk locations at any part of an office with- 
out the wiring being exposed. 

Where composition floors are specified an outlet in center of 
room and one just above the baseboard are provided. The 
wall outlet is used to carry the wire to the baseboard for running 
around room to desks, and not for a wall phone. 

Where two companies exist, two riser conduits between cabi- 
nets, two terminal boards, and two main conduits to switchboard 
room, terminated in opposite ends of room, are provided. Only 
one distribution cabinet and one branch conduit to each room 
are, however, provided in this case. 

Each junction cabinet will accommodate the equipment for 
distributing a 25-pair cable. 

In determining the cost of installing a branch exchange in a 
Federal building the following facts were considered : 



CONDUIT AND WIRING SYSTEMS 223 

Salary of operator, per annum $600 .00 

Rent of switchboard, per position per annum 24.00 

Rent of trunk lines, about 3, at $24 each 72 .00 

Messages, 2400 per annum minimum amount, at 2| cents 

each 60 .00 

22 stations on board, at $6 per annum each 132 .00 

(Where phones are located outside of main building, or 
private trunks exist between departments, add $24 for 
each such station.) 
Total cost of phone service per annum for switchboard and 

operator $888 .00 

One operator is provided for every 50 stations. 
Where a single line phone service is furnished, giving 600 calls 
per phone, the cost for 22 phones would be as follows: 

22 at $39 each ' $858 .00 

And 23 at 39 each 897.00 

As the telephone conduits are sometimes used for call bells, a 
lj-inch conduit is run between junction cabinets on each floor 
above the first, the conduits entering cabinet at opposite end of 
bottom to that used by the riser conduit. 

A special call bell system is installed for the post-office section 
of the building, with outlets located as follows : 

Near mailing platform on wall. 
< Screen near general-delivery window. 

Center of post-office workroom. 

Money -order and registry room on wall. 

Carriers' swing room on wall. 

Boiler room on wall. 

Postmaster's room in floor and wall. 

Assistant postmaster's room in floor and wall. 

To care for the battery leads of this call bell system a J-inch 
conduit is run from the junction cabinet to a suitable location in 
boiler room. Call bell outlets on screen are placed 4 feet from 
floor, and in an unfinished basement rooms near the ceiling. 

The cost of telephone conduit systems will average about $10 
an outlet. 

WEATHEE BUREAU SPECIAL CONDUITS 

In all buildings in which offices are assigned to the Weather 
Bureau, a large-size floor outlet box with brass cover is placed 



224 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

in the main office room of the Bureau, and a similar outlet box of 
waterproof type is located on the instrument platform on the 
roof of the building, these two boxes being connected by a 2-inch 
conduit for the reception of the instrument wires. The special 
outlet boxes are generally 6 inches square and 4 inches deep, and 
the cover of floor box in office room has an opening tapped in 
same for lj-inch conduit connection. 

In addition to the above, a conduit is run from the nearest 
cabinet and tablet of the lighting system of the building and is 
extended to the instrument platform on the roof and provided 
with a weatherproof outlet box at that point. One lighting cir- 
cuit is installed in this conduit. 

In buildings located on navigable waters, and which are pro- 
vided with quarters for the Weather Bureau, in addition to the 
above conduits a conduit is run from the nearest lighting cabinet 
and tablet to a weather-proof box on instrument platform. This 
conduit contains two lighting circuits which are controlled by 
snap-switches in the Weather Bureau office. 

In all cases a 1-inch conduit is taken from the vault-protection 
junction box previously noted and run to a floor outlet box in 
main Weather Bureau office for the reception of telegraph wires 
and messenger call-bell wires. 

CONDUIT FOR SIGNAL SYSTEMS 

In all buildings containing a court room, a conduit system is 
installed for the reception of wires for call-bells, intercommuni- 
cating telephones, etc., between .various portions of the building. 

The system consists of two 1-inch conduits, running parallel, 
and interconnecting floor boxes of special design located at vari- 
ous points throughout the building. From these floor boxes a 
f-inch conduit is run to a wall box just above the base board and 
another to a wall box just above the picture molding. If there 
is an adjoining office it is provided with similar outlets opposite 
and connected to the outlets above mentioned. One set of out- 
lets is placed in each office and in the workroom, money-order and 
registry room, and swing room; and a floor outlet is located in 
judge's platform in court room. The entire system is connected 
with the vault protection system by two 1-inch conduit. 



CHAPTER VII 
LIGHTING FIXTURES 

The present practice of the office is not to include lighting 
fixtures in the general contract for the erection and completion of 
a building but the lighting fixtures for several buildings are 
grouped and awarded as a separate contract. 

For the smaller buildings the requirements for lighting fixtures 
are standard, and the fixtures are delineated on standard-size 
office drawings, each fixture being given an identifying number. 

For lighting fixtures for the larger buildings special designs are 
used. 

Full size detail drawings of the most important fixtures are 
furnished manufacturers as the office has found it impossible to 
get satisfactory fixtures by any other means. 

BASIC DATA IN CONNECTION WITH DESIGN AND INSTALLATION OF 

LIGHTING FIXTURES 

As hereinbefore stated all Federal buildings except in the larger 
cities are wired for electricity and piped for gas, but combina- 
tion fixtures are installed only in the following locations: post- 
office workroom, post-office screen brackets, and brackets over 
lobby writing desks. Gas only brackets are also installed in up- 
per corridors and in basement. All other fixtures are electric 
only. This allows either gas or electricity to be used in spaces 
requiring light for extended periods and permits the use of simple 
economical fixture designs in offices, etc., where light is required 
only for short periods. 

Where combination fixtures are installed, inverted gas-mantle 
burners of a special design, developed to match the electric arms 
are used on fixtures in post-office workroom and on screen, and up- 
right burners (Welsbach Junior) on fixtures in public corridors for 
all floors. 

The inverted mantle-burner arms and the electric arms are al- 
ternately arranged on the body of the fixture. 

225 



226 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

In court rooms pendant fixtures are made for " electric only" 
service, and are hung with bottom of glassware about 15 feet 6 
inches from floor in rooms with 20 foot ceiling. The usual length 
of fixtures is 4 feet 6 inches for ceilings more than 20 feet high. 
In some cases pendants are dispensed with and special cove or 
ceiling lights are intalled. 

Portable desk lamps with an ornamental shade are used on 
the judge's desk. 

For the ordinary building, if the lobby desks are free standing 
and are arranged to receive a lighting fixture, they are equipped 
with suitable standards. 

Cord drops are used in boiler, storage, and machinery rooms. 
In basement they are fitted with porcelain shell sockets ; all other 
sockets have metal husks. Metal reflectors are seldom used on 
cord drops in basement. 

In the post-office workrooms special furniture lighting is in- 
stalled in accordance with standard office details. Metal shades 
and 15-watt lamps, allowing two lamps for each man, are used 
for this work. 

Pendant switches are used for all pendants in the post-office 
workroom and for pendants in office rooms where several fixtures 
are controlled by one wall switch. 

Open-flame gas burners on fixtures are never placed closer than 
18 inches to a ceiling; and 15 inches is the minimum distance for 
upright gas mantles. 

The height for pendants in office rooms will vary from 8 feet 6 
inches to about 10 feet, depending upon the size of room and the 
style of fixtures used; the minimum height being 7 feet. In post- 
office workrooms and other rooms where more than one outlet is 
needed the fixture height above the plane of illumination is one- 
half the distance between outlets for extensive type reflectors and 
four-fifths the distance for intensive type reflectors but fixtures 
are rarely hung over 15 feet above floor. The minimum height 
where mail bags are handled is 8 feet 6 inches. 

The architectural features are considered in selecting the de- 
sign of the lighting fixtures for the first-floor lobby, and their 
height will vary generally from 10 feet to 16 feet, depending upon 
the area illuminated and distance between the outlets. In lob- 
bies having less than a 13-foot ceiling, a ceiling-light globe fixture 
is generally used. 



LIGHTING FIXTURES 227 

In second and third-floor corridors the usual height for fixtures 
is 8 feet 6 inches ; in case of a low ceiling they may be hung 7 feet 
6 inches above the floor, but no lower. 

If a basement is less than 9 feet in height, separate gas brackets 
are used with " electric only" ceiling outlets provided with drop 
cords; or a ceiling fixture is used if the room is finished. 

Mailing vestibules with ceiling less than 10 feet require an "elec- 
tric only" ceiling outlet and a separate gas bracket. 

Bracket outlets are installed 7 feet above the floor as a general 
rule. 

The glassware used is of either the extensive or intensive types 
and both prismatic and opal glass is used. Opal dishes are used 
for semi-indirect lighting. Mirror reflectors and special glass- 
ware are also used to a limited extent. The reflectors used with 
inverted gas burners are the same shape and size as those used with 
electric lamps but are fitted with metal collars to avoid breakage 
due to the heat of the mantle. 

As a general rule not more than three sizes of tungsten lamps 
are used in any one building. Gem and carbon lamps are never 
used. 

The specification given at the end of this chapter will give 
further details of the requirements as to weight of metals, 
dimensions of glassware, etc. 

Reflectors are used for all lamps except in the boiler room, 
store rooms and attic. 

Finish of fixtures. Light oxidized brass finish is generally used 
for all fixtures installed in public lobbies, corridors, court rooms, 
and important office rooms, and oxidized copper is used in all 
other parts of the building and for mailing platform bracket. 
Brush brass finish is not used. 

In the larger and more important buildings special finishes are 
used to harmonize with the architectural treatment. 

ESTIMATING THE COST OF LIGHTING FIXTURES 

For preliminary estimating it is safe to say generally that the 
lighting fixtures will cost about the same as the conduit and wir- 
ing system. 

In Federal buildings a reasonably close approximation of the 
cost of the fixtures may be made by counting the number of fix- 



228 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

ture outlets and multiplying by $15 for combination fixtures with 
Welsbach mantles, by $14 for fixtures with plain gas burners, and 
by $13.50 for electric-only fixtures. If there is a courtroom the 
cost of fixtures for same should be determined separately, de- 
pending on type of fixtures, and be added to the above. 

The cost of installing fixtures will average for the entire country 
10 per cent of the value of the fixtures, though in the South and 
West 20 per cent will be nearer the figure. 

Special lighting on post-office workroom furniture costs approxi- 
mately $10 per light. 

The following is a typical lighting fixture specification prepared 
by the office : 

SPECIFICATION 

Combination of fixtures. Fixtures are to be of the combination 
type as designated in the fixture schedule. The fixtures are to be 
built for the number of electric and gas lamps as shown by sched- 
ule, regardless of the number shown in the drawings. All com- 
bination fixtures shall be provided with gas burners of type as 
indicated by symbol in the schedule, and fixture construction 
must correspond thereto. The plain lava-tip burners shall be 
furnished when mantle burners are not specified. 

"Electric only" fixtures. The construction of this type of 
fixture is to be the same as that of the combination fixture, with 
the omission of all gas burners and of all exposed attachments for 
same. The piping may be used as a passageway for the wiring. 

"Gas only" fixtures. The construction of this type of fixture 
is to be the same as that of the combination fixture with the omis- 
sion of all electrical parts. 

Glassware. All fixtures shall be equipped with glassware, free 
from flaws, and as noted in schedule. The mantle burners shall 
have glassware harmonizing in design, shape, and finish with the 
electric glassware on the same fixture, and shall be of size as in- 
dicated in schedule. 

Reflectors. The heights of reflectors over all (including collar) 
shall not be less than the following dimensions: 



LIGHTING FIXTURES 229 

T • Reflector 

Lamp sizes : height (inches) 

25-watt 4§ 

60-watt 5£ 

100-watt 5| 

150-watt 6| 

Reflex No. 3 T burner 5 

Reflex No. 4 T burner 4| 

Type E. Extensive type reflector, designated in schedule as 
"E," with numeral following to indicate the size of electric lamp 
in watts with which it is to be used, must give an apparent candle- 
power at 45° from the vertical axis between 10 and 60 per cent 
greater than at the vertical axis. 

Type I. Intensive type reflectors, designated in schedule as 
"I" with numeral following to indicate either the size of electric 
lamp in watts or the trade number of the gas burner with which 
it is to be used, must give an apparent candlepower at 45° from 
the vertical axis between 10 and 40 per cent less than at the ver- 
tical axis. 

All reflectors shall be of an approximate bowl shape, having 
inside surfaces smooth. The designs or patterns shall not be 
etched on nor cut in the glass, but shall be pressed or molded in 
the same, with outlines and elaboration of an artistic but not 
intricate character. Reflectors shall be made of pure white trans- 
lucent glass, shall appear white by both transmitted and reflected 
light, and bear surface patterns consisting essentially of panels 
and ribs; or shall be made of the best quality prismatic glass hav- 
ing a velvet finish on the inside. Such glass shall have inherent 
properties allowing a maximum diffusion with total absorption 
not exceeding 16 per cent. All reflectors shall give a uniform dis- 
tribution about the vertical axis, and each type shall be uniform 
as regards dimensions, ornamentation, and distribution curves. 
All reflectors in this building must be of the same manufacture. 

Type G. Globes, designated in schedule as "G" with num- 
eral following to indicate the diameter required are to be of dif- 
fusing glass of sufficient density to produce uniform brightness 
over the entire surface and with an absorption not exceeding 25 
per cent. The surfaces shall not be cut or roughed in any manner, 
and are to bear outside surface designs of an artistic but not in- 
tricate elaboration either pressed or molded in them. Such glass 



230 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

shall consist of two hemispheres held together by an equatorial 
hinged metal band giving access to the lamp, shall have surface 
patterns consisting essentially of panels and ribs and appear white 
by both transmitted and reflected light ; or shall consist of a two- 
piece globe of best quality clear prismatic glass giving efficient 
downward distribution; the lower piece of prismatic globes shall 
have a satin finish on the inside. All globes are to be made so 
that they may be readily secured to and detached from the fix- 
tures with which they are specified and shall be uniform as re- 
gards shape and ornamentation. Globes 8 inches in diameter 
and smaller shall be as above specified except that they may be 
made in one piece. 

Type S. Special glassware for bowls and special dishes shall 
be equal in quality to the globes and have ornamentation sub- 
stantially as shown on the drawings. Such glass shall in all cases 
be made of dense opal or white glass and of size as shown on the 
drawings unless otherwise noted in the schedule. 

The contractor must replace all glassware installed by him 
which may be broken or damaged prior to time of final inspec- 
tion, as all glassware must be complete and free from all defects 
at time of final inspection. 

Metals. All exposed parts of fixtures are to be made of brass. 
The composition of brass shall be approximately 1 part zinc and 
2 parts ingot copper. If the contractor desires to use other al- 
loys in lieu of those herein specified, the composition of the same, 
together with finished samples of the metals, must first be sub- 
mitted to the Supervising Architect for approval. 

Castings. All patterns for casting shall be of metal, hand 
chased, and perfectly finished. The modeling of patterns must 
be crisp and spirited, true to detail, and uniform in execution. 
The castings shall have have ample metal for strength and rigidity 
and for a substantial appearance. They shall be close grained, 
free from sand and blowholes, and free from discoloration. All 
details of cast ornamentation must be plainly brought out by 
hand finishing. Where ornaments are made in parts, the joints 
must be brazed and made so as to cause no break in the orna- 
mentation. 

Casings, shells, canopies, etc. Casings, spun canopies, and 
shells up to and including 8 inches diameter shall not be less than 



! 



LIGHTING FIXTURES 231 

No. 20 Brown & Sharpe gauge metal; shells above 8 inches diame- 
ter shall not be less than No. 18 Brown & Sharpe gauge metal. 
Both gauges apply to the thickness of metal before spinning, but 
the thickness of metal after spinning shall not be reduced at any 
point more than 20 per cent. The size of casing shall in no case 
be smaller than shown on drawing, and in all cases must be of 
ample size to provide room for the wiring. All tubing must be 
seamless drawn, and if used as a supporting member of the fixture 
must not be less than No. 17 Brown & Sharpe gauge. The cano- 
pies shall not be insulated from the walls and ceilings. Set-screw 
collars for canopies shall be at least J inch in thickness, and the 
collars must fit the stem closely. All curved and bent parts of 
fixtures shall be true and free from kinks or bruises. All seats 
between tubings or casings, seating rings, castings, shells, and 
other parts shall be so closely fitted that all parts will be held 
tight, forming concealed joints. Canopy rings and seating rings 
shall be of solid brass turned to size. All burrs, fins, and 
sharp edges must be removed from fixture parts before same 
are assembled. 

Gas piping. The gas piping of fixtures shall be: For fixture 
arms, J inch; fixture stems, f inch; standard galvanized pipe, un- 
less otherwise shown on drawing. Ends of gas piping to be 
reamed to the full area of the pipe. All joints must be cemented. 

Wiring. Fixture wire must be in strict accordance with the 
latest specifixation of the National Board of Fire Underwriters. 
The carrying capacity of the wiring shall correspond to the Na- 
tional Electrical Code requirements. No wire shall be smaller 
than No. 16 Brown & Sharpe gauge. All joints in wiring must 
be soldered and well insulated with rubber and friction tape. 
At all points where abrasion is liable to occur the insulation of 
the wire must be reinforced with tape or tubing. All wiring must 
be concealed within the fixture construction, except where chain 
stems are specified. The exposed wiring of chain-supported fix- 
tures shall have a silk outer braid of color to match the fixture 
finish; single wires to be woven in the chain in the most incon- 
spicuous manner. Sockets shall be wired in multiple. 

Reflector and globe holders. All reflector holders shall be sup- 
ported from and rigidly attached to the fixture army or body, 
shall be made in accordance with the dimensions shown on draw- 



232 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

ing, and be provided with a reinforcing ring having a closed joint. 
Cast holders shall be made as shown and be provided with holes 
for ventilation. Spun holders for globes shall be made similar to 
the 2i-inch holders and of such length as to bring lamp filament 
in center of globe, using electrolier sockets. 

Switches. Pendent push switches shall be single pole, single 
point, 5 amperes, 125 volts, National Electrical Code standard. 
The switches shall have sufficient length of No. 16 Brown & Sharpe 
gauge silk-covered reinforced lamp cord to bring same within 6 
feet 6 inches of floor. Canopy switches shall be National Elec- 
trical Code standard of the push-and-pull type. 

Insulating joints. No insulating joints are to be used. 

Sockets. All metal shell sockets shall be National Electrical 
Code standard, Edison-base keyless type of either the electrolier 
or standard size as required, and where not entirely concealed 
by the glassware holders, shall be finished to match the fixtures. 

Gas burners. All ''gas only" and combination fixtures not pro- 
vided with mantles shall have 5-foot lava-tip gas burners. Fix- 
tures denoted in schedule with the symbols ( '3T" are to be 
equipped with "Welsbach Reflex No. 3 T" burners; fixtures de- 
noted with the symbol "U 59" are to be equipped with "No. 59 
Welsbach Junior" burners. 

Finish of fixtures. The finish of fixtures is noted in schedule. 
It must be produced in the most durable manner by electroplat- 
ing and acid-bath processes. No paints or pigments shall be 
used to produce any finish. Oxidized copper finish is to be a 
dark copper color; tone to be even and to be obtained by hand 
scouring. Light oxidized brass finish shall have the metal highly 
polished to a yellow brass color and then oxidized to a dark color 
before scouring, enough of the dark color being left in the scouring 
operation to make it scarcely visible on casings, bodies, and other 
high surfaces, while low portions of both spun and cast orna- 
ments are to be left dark. All finishes shall have an even coat of 
lacquer. Upon application of the contractor to the Supervising 
Architect samples of the various finishes above described will be 
forwarded to the contractor for his guidance. 



LIGHTING FIXTURES 



233 



SCHEDULE OF FIXTURES 

Abbreviations in schedule: 0. C, oxidized copper finish; L. O. B., light oxi- 
dized brass finish; 3 T.; reflex No. 3 T. burner; I. 100, intensive type 
reflector for 100-watt lamp; 1 3 T., intensive reflector for No. 3 T. burner; 
G., globes, etc. Tungsten lamps used. 



w 
K 

P5 p 
« » 


^ 2 


GAS 

LAMPS 


ELECTRIC 
LAMPS 


LOCATION 


FINISH 


REFLECTOR OR 
GLOBE TYPE 


En H 




No. 


Kind 


No. 


Watts 


Gas 


Electric 


x 3 














FIRST FLOOR 








ft. in. 


3 


532 







1 


100 




L. O. B. 




G. 12 in. 


5 


2 


563 


1 


3 T. 


1 


25 


Public lobby 


L. O.B. 


G. 6 in. 


G. 6 in. 




1 


569 







3 


100 




L. O.B. 




S. 20 in. 


3 


3 


510 







1 


25 


2 toilets and sink room. . 


L. O.B. 




I. 25 




6 


534 


2 


3T. 


2 


100 


Post-office workroom 


O. C. 


I. 3T. 


I. 100 


5 6 


2 


534 


2 


3T. 


2 


100 


Post-office workroom at 


O. C. 


I. 3 T. 


I. 100 


2 2 


7 


530 


1 


4T. 


1 


25 


Post-office workroom 
screen 


O. C. 


I. 4T. 


I. 25 




2 


534 







2 


100 


Money-order and regis- 
try division 


O. C. 




I. 100 


2 


3 


570 







1 


25 


Money-order and regis- 
try screen 


O. C. 




I. 25 




1 


623 

604 



1 


Tip. 


1 



25 


Mailing vestibule 


O. C. 
O. C. 




I. 25 




1 






1 


510 





1 


25 


0. c. 




None 






BASEMENT 






3 


623 







1 


100 


Swing room and toilet. . 


0. c. 




I. 100 




3 


510 


1 


Tip. 


1 


25 


Passage, toilet, and over 
sink 


0. c. 


None. 


I. 25 




13 


504 







1 


25 




0. c. 




None 


2 6 


2 


604 


1 


Tip. 







0. c. 


None 















Shipment of fixtures. Lighting fixtures shall be wired and 
sockets connected at the factory when the fixtures are made. 
They shall not be shipped in a knocked-down condition but shall 
be assembled in so far as possible to facilitate shipment/ Fix- 
tures having arms must have same connected tight to the body 
and whenever possible all fixtures shall be shipped assembled 
and ready to install. 

Length of fixtures. The length of 'fixtures given in the schedule 
is the distance from the ceiling to the bottom of the lowest piece of 
glass ware (reflector or globe) on the fixture, and where no glass- 
ware is called for the lowest part of fixture shall determine the 
length. 



234 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Installation of fixtures. All fixtures shall be hung from the gas 
piping of the building or from fixture studs. All pendent fixtures 
shall be plumb and bracket fixtures at right angles to walls. 

Temporary drop cords. In event of any delay in receipt of sat- 
isfactory lighting fixtures at the building, or in the event that the 
lighting fixtures at the building are rejected and it is deemed neces- 
sary by the superintendent to furnish light to the entire building 
or any part thereof the contractor must, at his own expense, in- 
stall such temporary drop cords as the superintendent directs and 
maintain them in safe and satisfactory condition until satisfactory 
lighting fixtures are furnished and installed. 

Inspection and test of fixtures. After the fourth test has been 
made on the gas-piping system, as specified under head of "Gas 
piping" in the specification and said test has been certified as 
satisfactory by the superintendent, the lighting fixtures may be 
hung and attached to the gas piping when the conditions at the 
building (as determined by the contractor) warrant. 

After the fixtures have been connected to the gas piping the 
entire gas piping and fixtures must be tested and proved tight 
under an air pressure of 4 inches of mercury. Test pump and 
mercury-gauge column must be furnished by the contractor. 

After fixtures are connected to the wiring system of the build- 
ing the entire wiring system and fixtures must test free from short 
circuits and grounds and must show an insulation resistance be- 
tween conductors and between conductors and ground, based on 
maximum load, not less than the requirements of the latest edi- 
tion of the National Electrical code, counting full current at 110 
volts required with all lamps in service. 



CHAPTER VIII 
ELEVATORS 

WITH SPECIAL REFERENCE TO INSTALLATION IN FEDERAL BUILDINGS 
UNDER CONTROL OF THE TREASURY DEPARTMENT 

In deciding upon the number, type, and speed of elevators for 
modern structures, architects have not been giving the subject 
the careful preliminary study which its importance demands, and 
the unfortunate results may be noted in many recently-erected 
buildings with an elevator equipment that has proved wholly in- 
adequate. 

With the aid of individual experience and judgment, a close ap- 
proximation of the number of elevators which should be installed 
in a given building may be based on the following facts in regard 
to elevator service as stated by Mr. R. P. Bolton, a prominent 
consulting engineer of New York City, in his excellent treatise 
entitled " Elevator Service." 

Tenants object to waiting more than thirty seconds for a car, 
or, in other words, demand a schedule not exceeding thirty seconds. 

The occupancy of first-class office buildings in large cities will 
vary from one tenant for 100 square feet of rentable floor area in 
brokers' offices to one tenant for 150 square feet in office buildings 
devoted to real estate agents, etc., on the less important streets. 

In first-class apartment houses it will average one tenant to 
300 square feet rentable floor area, and in modern high-class hotels 
one to 240 square feet. For preliminary calculations for the av- 
erage office building with mixed tenancy, one tenant to 150 square 
feet may be assumed. 

The rentable area in an average office building is generally 60 
per cent of the gross area. 

The maximum passenger-carrying capacity of an elevator is 
reached when the car stops at 80 per cent of the number of floors 
which the elevator is designed to serve. 

An elevator should be designed on the basis of making 80 per 
cent of its landings to handle the tenants of the building one way 

235 



236 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

in one-half hour, if their occupations are of a character which in- 
dicate that the majority will begin and stop work at about the 
same time. 

The average load carried by the elevator is equal to 40 per cent 
of the number of floors served multiplied by 150 pounds. 

The speed of local elevators in a modern office building of more 
than ten stories should be at least 400 feet per minute, and the 
speed of express elevators should be approximately 600 feet per 
minute. 

In estimating the round-trip time of an elevator is has been 
found that approximately six seconds is required to receive and 
discharge each passenger : and to this should be added nine seconds 
for time lost at upper and lower landings in handling gates. 

The round-trip time of an elevator in a good office building va- 
ries between 1^ and 3 minutes, depending upon height of building, 
speed of elevator, etc. As a general rule, the time allowed for a 
round trip should not exceed 2 J minutes. 

With above data, and knowing the gross floor area of a building 
and the number and height of stories, the elevator equipment 
and its duty can be determined. 

Assume a building with a total gross area of 140,000 square 
feet and a height of 168 feet above the first floor divided into 
fourteen stories. The rentable area will be about 60 per cent of 
130,000 (the area above first floor) or approximately 80,000 square 
feet. Assuming an occupancy of one tenant to 150 square feet, 
the number of tenants to be handled by the elevator in one-half 
hour is 533, or 1066 per hour. 

There being thirteen landings to be served above the first floor, 
the number of passengers per trip one way each elevator will be 
80 per cent of 13, or say, ten passengers. As each elevator will 
on an average take ten persons per trip, it is necessary to know 
the round trip time to arrive at the capacity per hour. Ten pas- 
sengers will require sixty seconds to enter and leave car, to which 
must be added nine seconds for time lost at terminal landings, plus 
actual running time. The speed in this example will be assumed 
as 400 feet per minute, or an average speed of 5.33 feet per second, 
making due allowance for retardation, etc. 

To run 156 feet X 2, or 312 feet, the time will be 312 -^ 5.33, 
or, approximately, 58 seconds; and the total time will be 58 + 



ELEVATORS 237 

60 + 9 = 127 seconds, which is well within the limit set of 2\ 
minutes for a round trip. This speed will give approximately 
twenty-eight round-trips per hour and each car will then handle 
28 X 10 = 280 persons; and as the total number of persons is 
1066 per hour, four elevators will be sufficient. The schedule will 
be the round-trip time divided by the number of elevators, or 2 
minutes divided by 4, giving 30 seconds, which is the schedule 
desired. 

The area of the car floor in the example given would be 10 X 2 
+ 4 = 24 square feet, as an allowance of a 2 square feet is made for 
each passenger and 4 square feet for the operator. The car should 
be close to 6 feet, measured between rails, and 4 feet deep. The 
average number of passengers carried per trip will be 40 per cent 
of the number of floors served, or 13 X 0.4, say 5; and assuming 
the weight of each passenger and of the operator as 150 pounds, 
the result (5 X 150) + 150 = 900 pounds, the average load car- 
ried by the elevator. 

As a very rough guide in preliminary calculations for Federal 
buildings one elevator for 25,000 square feet of floor area may be 
assumed as satisfactory. 

Before completing the drawings for a given building it is advisa- 
ble to take up the elevator problem with some first-class elevator 
company, as the elevator equipment is a strong factor in the suc- 
cessful administration of a building, especially an office building. 

In his treatise, hereinbefore referred to, Mr. Bolton brings out 
certain points about elevator service which are frequently over- 
looked by architects and engineers. At least two of these points 
should be always kept in mind, i.e., that in high buildings the 
elevators should be capable of quickly emptying the upper floors 
in case of a fire; and that in the design of any plant sufficient re- 
serve capacity should be allowed so that elevator repairs may be 
made during regular working hours without inconvenience to the 
occupants of the building. 

The elevators should always be grouped, and occupy a prominent 
position in relation to the building entrance. 

Size of cars. As previously stated, in proportioning the size of 
the platform for passenger elevators for large and tall office build- 
ings, it is assumed that a car will stop at 80 per cent of the land- 
ings for which the elevator is designed to stop ; that one passenger 



238 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

is estimated to be discharged at each of said floors; and that 2 
square feet per passenger and 4 square feet for the operator are 
allowed in determining the minimum size of car. This size should 
also be nearly the maximum and the final size of the car should 
not vary much from this determination, for the reason that a 
large car means more passengers, longer stops, and consequently 
a schedule slower than that for which the plant was designed. 

When installing a passenger elevator in an old Federal building 
where no hatchway was originally provided, the minimum size of 
car is made 4 feet 6 inches x 4 feet 6 inches. This is an unde- 
sirable size and is used only where the conditions demand it. 

In old buildings where conditions permit and in all new build- 
ings, the cars are made 6 feet wide measured between the rails, 
and 5 feet deep. A wide and shallow car is much more desirable 
than a square car, or a car with a great depth and a narrow di- 
mension between rails, as passengers have a tendency to crowd 
to the front of a car. No car should be larger than 6 feet x 6 
feet except in a department store, where an 8 feet x 6 feet deep 
car should be the maximum. 

The use of pilasters in cars is not desirable and should be dis- 
couraged. 

In Federal buildings the cars for freight elevators, mail lifts, 
and bonded wareroom lifts are made 6 feet x 6 feet, which is the 
most desirable size. Ash-lifts and hand-power mail-lifts are gen- 
erally made 4 feet x 4 feet, and cars for electric dumb-waiters 3 
feet 4 inches x 3 feet 4 inches. 

Elevator hoistways are made 1 foot 1 inch wider than car to 
allow for the guide rails and 9 inches to 12 inches deeper than 
car, the front of car being kept 1\ inches away from the entrance 
threshold. 

In office buildings up to 10 stories the car should be 5 feet 
wide measured between the rails and 4 feet 4 inches deep. From 
10 to 15 stories the cars should be approximately 6 feet wide and 

4 feet 4 inches deep; and from 15 to 19 stories, if all elevators are 
local, the cars should be approximately 6 feet 6 inches wide and 

5 feet deep. 

In the average first-class office building, or in a Federal building, 
the cost of the ornamental car should range between $300 and $500. 
Any increase over $500 is extravagant, as, for instance, in install- 



ELEVATORS 239 

ing special, solid bronze cars. The electroplating of iron is just 
as satisfactory and much cheaper. 

Emergency exits should always be specified for passenger cars. 
If cars are in a separate hatchway, the emergency exit should be 
in top of car, and where two or more cars are in the same hatch- 
way, emergency exits should be provided from one car to another. 

A car with two entrances is dangerous and objectionable. 
When conditions demand two opposite entrances, a collapsible 
gate or sliding panel in the car should be used at the entrance 
further from the operator; and entrance door and gate on car 
should be operated by an approved device, which on electric ele- 
vators should be made interlocking with the controller. If the 
entrances to the car are on adjacent sides, the entrance gate further 
removed from the operator should be protected by some device, 
which, on electric elevators, should be interlocking with the con- 
troller. 

Speeds. The determination of the speed at which a car should 
be operated is a matter of judgment, and is governed by the rise 
of the elevator, whether the service is express or local, the number 
of stops, and the time taken to discharge passengers. 

In apartment houses the car speed under ordinary conditions 
should be not over 200 feet per minute. 

In departnent stores the speed should not exceed 250 feet per 
minute nor should it fall much below that where cars stop at each 
landing up and down. 

In hotels higher speeds should be used, depending on the height 
of building. 

In office buildings below 10 stories in height, the speeds will 
vary from 200 to 400 feet, while with 10 to 15 stories a speed of 400 
feet should be allowed. 

Express elevators equal in number to the local elevators should 
be used in practically all buildings sixteen stories high and over, 
and in very tall buildings may be run at 700 feet to 800 feet per 
minute until they reach their first landing. In very tall buildings 
where the ground area is small it is better to run all elevators 
local rather than to have part local and part express. In New 
York City 500 feet per minute is the legal limit of speed for local 
elevators and 700 feet per minute for express service. An eleva- 
tor is rated as f ''express" when it has a clear run of 80 feet with- 
out a stop. 



240 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

Federal buildings are nearly always low, and consequently ele- 
vator speeds are comparatively low. The following are used : 

Speed in feet 
Travel of car per minute 

f30 to 40 feet 200 

Passenger Elevators \ 45 to 70 feet 250 

[75 and over 300 

f 25 to 35 feet 100 

Freight Elevators \ 35 to 75 feet 150 

[75 and over 200 

Electric Dumb Waiters 30 and over 100 

[ 10 feet 25 

Hydraulic plunger mail and freight lifts \ 30 feet 50 

[Over 30 100 

Loads. The maximum load to be lifted by any passenger 
elevator should be arrived at by allowing 75 pounds for each 
square foot of car floor area. The speed-load should be based on 
about 80 per cent of the above loading. 

Strictly freight elevator loads can be determined only upon de- 
tail knowledge of the duty the elevator is expected to perform. 

Nearly all offices buildings have one or more passenger cars 
designed for lifting safes, which ordinarily will not weigh in ex- 
cess of 6000 pounds each. 

The standard passenger elevators in small Federal buildings 
have a speed load of 1800 pounds and a maximum load of 2200 
pounds. 

Freight elevators in Federal buildings never have a capacity of 
less than 3000 pounds, and the load in large cars is usually based 
on 100 pounds per square foot of car floor area. 

Hydraulic plunger lifts for freight and mail are seldom designed 
for a capacity of less than 2000 pounds. Where a hydraulic 
plunger lift must be operated with city water pressure at about 
50 to 60 pounds, and structural conditions prevent counterweight- 
ing, the load is reduced to 1000 pounds. 

The capacity of hand-power mail-lifts and electric dumb-wait- 
ers is made 400 pounds. 

The hand-power freight-lifts used cover about the following 

range : 

3x3 platform 500 capacity 

4x4 platform 800 capacity 

5x5 platform 1000 capacity 

5x6 platform 2000 capacity 



ELEVATORS 241 

A hand-power freight elevator is installed only as a last resort, 
and is not advisable. 

Types of Elevators. Hydraulic passenger elevators, except the 
plunger type, which is especially popular for department stores, 
have practically given way to electric elevators which are now 
generally used under all conditions where direct current is avail- 
able, and have reached a high plane of safety and efficiency. 

The hydraulic freight elevator has a limited field, and is gener- 
ally confined to the short-rise plunger type, which gives a rugged 
and generally satisfactory elevator when operated at moderate 
speed. 

The hydraulic-plunger passenger elevator is very satisfactory 
for a rise of not over 150 feet, and for speeds not in excess of 350 
feet per minute. The pressure-tank system should be used with 
this type of elevator and the water-pressure carried should be 100 
to 175 pounds per square inch. 

The horizontal low-pressure hydraulic pushing or pulling type, 
the vertical low-pressure hydraulic pulling type, and the still older 
steam type of elevators are seldom installed. 

The leading elevator builders do not recommend the use of 
alternating current for passenger elevators when the speed exceeds 
250 feet per minute, nor the use of single-phase current for any 
elevator with a motor in excess of 15 H.P. For a tall building 
where an isolated generating plant is not to be installed and only 
alternating current is supplied by the local company, they rec- 
ommend the intallation of direct current elevators operated by 
motor-generator sets which will transform the alternating current 
into direct current. The claim is made that the operating cost 
with this outfit will be less than for hydraulic elevators except 
in climates where exhaust steam for heating is required the year 
around and in department stores where the speed should not 
exceed 250 feet and elevators make all stops and the rise is short. 

If direct current is available, and investigation shows that no 
special conditions demand hydraulic equipment, the selection of 
the elevator mechanism involves only the selection of the particu- 
lar type of machine best suited to the service. 

In commercial practice, the standard, single screw, electric, 
drum machine is recommended for passenger service for speed 
loads varying between 1600 and 2000 pounds and for speeds 
ranging from 100 to 175 feet per minute. 



242 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

The standard double-screw, electric drum machine is recom- 
mended for passenger service for all loads from 2000 to 4500 
pounds, and for speeds from 175 to 300 feet per minute. This 
type of elevator is almost exclusively used in Federal buildings. 
These machines may be arranged for back gearing so that they 
can handle 6000 pounds or more in buildings where safes must be 
handled. 

The single and double-screw machines should be placed in the 
basement unless special conditions forbid, in which case they 
may be located over the hoistway. 

The worm-gear traction machine is recommended for speed 
loads ranging from 1600 to 4500 pounds and for speeds ranging 
from 250 feet per minute as a minimum to 400 feet as a maximum. 
These machines may be back-geared so that heavy loads like safes 
may be lifted. When the machine can be located at the top of 
the hoistway, and the speed of car is 300 feet per minute or more, 
this type of elevator is strongly recommended in preference to 
the single or double-screw drum machines. It may also be lo- 
cated in the basement if desired. Its cost is about 10 per cent 
more than the double-screw drum type. 

The worm-geared traction type of elevator possesses many 
points of superiority over the drum machines, among the most 
important being the feature of the design which prevents over- 
running of the car or counterweight beyond a predetermined limit 
of travel; the absence of side leading of cables; the use of ball 
bearing shackles on all rope hitches, preventing torsional strain 
on cables; and the use of oil or spring buffers under both the car 
and the counterweights. Spring buffers are used when the speed 
does not exceed 300 feet per minute. 

The gearless traction type of machine which is the latest and 
most satisfactory production of the elevator industry, is recom- 
mended for use in all cases where the speed loads vary between 
1600 and 3500 pounds and where the speed is to be 400 feet and 
over. There is practically no limit to the speed of these ma- 
chines and in express service they can readily be operated at' 800 
feet per minute. 

The two-to-one gearless traction type of elevator may be used 
under the same conditions as given above for the worm-gear trac- 
tion type, with the addition of a traveling sheave placed on both 



ELEVATORS 243 

car and counterweight. This type of elevator is being used to 
advantage between the given limits of speeds as applied to the 
worm-gear traction machines where economy in current con- 
sumption is a governing feature. 

These machines should always be located at top of hoistway, 
though it is possible to place them in the basement. 

For lifting heavy loads the speed is reduced by special appli- 
ances and an extra brake installed. 

Adjustable counterweights may also be used with the worm-gear 
traction and the gearless type machines so that 6000 to 7000 
pounds loads may be handled. 

The gearless type of elevator costs more than the other electric 
types, but is considerably more efficient. 

When the only current available is single-phase other than 60- 
cycle, special consideration must be given to the type of elevator 
to be used, as definite practice has not been established for guid- 
ance in such cases, although elevator manufacturers are rapidly 
advancing along this line. 

In Government practice, low-rise freight elevators, and mail, 
ash, and bonded-wareroom lifts are made direct plunger hydraulic. 
A lift is always provided for a bonded wareroom. In the large 
Federal buildings provision is made for the installation of a direct- 
acting plunger ash-lift or an electrically operated ash conveyor. 

Where the post-office workroom floor is more than 5 feet above 
grade of driveway, hydraulic plunger elevators are installed to 
handle mail. When special conditions demand, in the small build- 
ings, hand-power elevators are installed to handle mail. 

In Federal buildings three or more stories in height, especially 
when a court room is on second or third floor, provision is made for 
the installation of one or more electric passenger elevators. 

Owing to the many special conditions imposed by each layout, 
it is difficult to predict the efficiency of electric elevators from line 
to load, but as a rough rule it is safe to say that the efficiency of 
the double-screw drum machine will average 50 per cent; the 
worm-geared traction machine, 55 per cent; and the gearless 
traction type, 65 per cent. 

The kilowatt consumption per car mile is dependent on the 
number of stops, but for drum machines in Federal buildings it 
will usually average 5 kilowatts per car mile. 



244 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

The car travel in office buildings will range from 10 to 20 car 
miles per day, the latter figure being the average for a well-occu- 
pied building. In the Singer Building in New York City it is 
stated that the tower elevators will each average thirty miles per 
day. 

In the ordinary Federal buildings the travel for each passenger 
elevator will average eight car miles per day and the average cost 
of current for an electric elevator will be $25 per month. In the 
largest cities the car travel will average nearer twelve car miles 
per day. 

In the operation of hydraulic elevators 8 water horse power 
per car mile is a fair average. 

To ascertain the approximate size of the horse power of the 
motor for an electric elevator multiply two-thirds of the maximum 
load by the speed in feet per minute and divide by 16,000. Ex- 
cept under special conditions an elevator should not be over- 
counterweighted more than 40 per cent of the maximum load. 

Space requirements, etc. When elevators of any type are 
placed at the top of hoistway a 7-foot 6-inch clear space should be 
allowed to nearest point of roof or to the underside of pent-house. 
This should be increased to not less than 10 feet wherever possible, 
and an I-beam trolley rail with chain fall installed to facilitate 
the handling of elevator parts during erection or repairs. 

The minimum distance to allow from the top landing to top of 
machine beams for overhead traction elevators is 17 feet when 
the speed does not exceed 400 feet per minute, and 19 feet when 
the speed is in excess of 400 feet. 

In Federal buildings where the drum type of elevator is used 
the minimum distance from the top landing to the underside of 
lowest point of roof is made 20 feet. 

With counterweighted plunger elevators and electric dumb- 
waiters the minimum distance allowed from the top landing to 
the lowest point of ceiling or roof is 14 feet. 

The overhead clearance for electric elevators of all types is one 
of the most important safety items and in Federal buildings it is 
never made less than 3 feet for direct current elevators and not 
less than 4 feet for alternating current elevators, the distance be- 
ing measured from the top of the car shoes. 

The distance from the car floor to the top of the shoes is gener- 



ELEVATORS 245 

ally 10 feet 7 inches, but under unfavorable conditions the cross- 
head may be sunk into the roof of cab and this distance reduced 
to 9 feet 7 inches. 

The minimum depth of pit for any electric drum elevator should 
be 3 feet 6 inches for direct-current and 4 feet for alternating- 
current elevators. 

The minimum depth of pit should be 6 feet where oil buffers 
are used and 4 feet with spring buffers. 

When worm-geared traction elevators are located at top of the 
hoistway the rear wall of pent-house may be carried up about 
flush with the rear line of hoistway. At the front of the elevator 
a space at least equal to the depth of the hatchway must be al- 
lowed for the machine, and at each end of the elevator bank a 
space equal to at least one-half the width of the hoistway of one 
elevator should be allowed. 

The most fertile source of trouble in installing elevators is the 
failure of architects and engineers to make proper allowance of 
space for the installation of the machinery and too much impor- 
tance cannot be attached to this feature. 

The location of an elevator machine directly under the hatch- 
way is extremely poor practice and should be avoided unless space 
conditions forbid any other course, or the use of auxiliary leading 
sheaves would be necessitated by locating machine outside of 
hoistway. 

In Federal buildings where it is necessary to locate a machine 
under the hoistway, the minimum distance from machine room 
floor to under side of the pit-pan at first floor is made 8 feet 6 
inches ; and where conditions will permit of lowering the machine 
room floor, the distance is made 9 feet 6 inches. 

Where the car runs to basement and the hoistway is enclosed in 
brick walls, the minimum opening in the wall of the shaft for the 
drum for standard elevators should be 8 feet 6 inches high and 4 
feet wide and where possible it should be made the full width 
of shaft and 9 feet high. 

If natural light is not available at location of overhead work, 
convenient and ample artificial illumination should be provided. 

Particular attention should be given to the fact that the inside 
edge of entrance door thresholds must be absolutely plumb from 
top to bottom so that the distance from car floor to thresholds 



246 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

will be the same at all floors. Where conditions require a pro- 
jection in the hoistway at entrance door, it should not be made 
sharp but be flared off at a slight angle. 

In locating entrance doors to elevators consideration should be 
given to the fact that the operator should handle the controller 
with the left hand and open and close the door with right hand. 
The door should slide from right to left. Special efforts are made 
in Federal buildings to obtain a first-class hanger and operating 
device on hand-operated doors. 

The minimum width of opening for entrance door for a passenger 
elevator should be 2 feet 6 inches. The height of entrance doors 
should always be 7 feet. The two-panel entrance door, each leaf 
opening from the center, is a first-class door and either this type 
or the two-third opening door, one panel sliding on the other, 
should be used wherever possible, as the service of an eleva- 
tor is materially affected by the size and type of the entrance 
door. 

The entrance door should be as light as possible in weight, and 
be placed close to hoistway so that the operator does not have to 
let go of the controller in order to operate the door. Where the 
entrance door is heavy, or where the service is heavy and speed 
of operation is an item, the compressed-air system of door hand- 
ling is installed. 

The elevator machine (especially if for alternating current) 
should be installed in a machine-room with brick enclosing walls 
to reduce the noise to a minimum. 

For each passenger and freight elevator, a grating designed bo 
support a load of 75 pounds per square foot should be placed be- 
neath the overhead work. 

The best overhead grating is made of 2-inch channel irons with 
perforations set so that a 1-inch space exists between channels. 

On all electric elevators with lift of 15 feet or over, and on hand- 
power elevators on which persons may ride, a safety device which 
will become operative upon breaking of hoisting cables should be 
installed. For 15 feet to 20 feet lifts, the quick-acting type which 
acts immediately upon attaining excessive speed or upon breaking 
of hoisting cables should be used. For lifts over 20 feet the regu- 
lar guide grip safety device actuated by a centrifugal governor 
should be used. 



ELEVATORS 247 

Attention should be given to the design of the enclosing grille 
work of elevator hoistways and every effort made to have all 
openings below door transoms kept down to \\ inches in width 
which will conform to the best practice in this respect. 

The platforms of all freight and mail lifts should be enclosed 
on three sides and have a ceiling. The distance from floor to 
ceiling of enclosure on platform should be 7 feet. The lower part 
of enclosure should be \ inch sheet iron or lighter weight corru- 
gated iron, and upper part and ceiling No. 9 B.W.G. galvanized 
wire with 1-inch diamond mesh. 

To operate the sidewalk doors, in connection with an hydraulic 
plunger lift, in Federal buildings, four rods are attached to the 
underside of the cover. These rods are of sufficient length to 
extend into four (4) 2-inch pipe uprights, attached to the lift 
platform. On the rods under the cover heavy rubber or spring 
buffers are placed. The cover is made of f-inch sheet steel in 
one piece. In lieu of this, a bow or bale is sometimes placed on 
the elevator platform to operate hinged double-leaf doors at side- 
walk level. 

When it is necessary to place an hydraulic elevator in an ex- 
posed location subject to freezing temperature, some non-freezing 
mixture should be used as the operating medium instead of water. 
In plants where oil is used a weighted accumulator should be in- 
stalled instead of the usual pressure tank. In Federal buildings 
all car and counterweight guides for passenger and freight eleva- 
tors, hydraulic lifts, and electric dumb-waiters are steel. Car 
guides are not less than 4 \ inches x 3f inches, weighing not less 
than 14 pounds per foot ; counterweight guides weigh not less than 
7 pounds per foot. The car guides are backed up with 7-inch 
channels weighing 9 J pounds per foot. 

For hand-power lifts the car and counterweight guides are kiln- 
dried maple. 

To ascertain the strain on the supporting beams with the eleva- 
tor machine located at the top of the hatchway, the weight of 
the standard double screw machine is taken at 15,000 pounds in 
Federal buildings. 

In designing the overhead supports, the live loads are doubled 
and added to the dead loads and the calculation for supporting 
beams is based on a fibre strain of 8000 pounds in the section used. 



248 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Mechanical dial indicators should be installed in small buildings 
having one or more elevators. In buildings requiring three or 
more elevators in one group, the flashlight-signal system should 
be installed, with mechanical dial indicators on the first floor. The 
flashlight signal system will increase the capacity of a passenger 
elevator plant approximately 10 per cent, and is worthy of serious 
consideration. 

Cables and counterweights. Swedish iron hoisting and counter- 
weight cables are used in commercial practice, and also in Govern- 
ment practice, except where special conditions render it advisable 
to use " steel" cables. The use of ropes larger than f-inch diame- 
ter is not desired unless loads exceed safe working strain. The 
following table is used in selecting cables for passenger elevators: 





Min. 


diameter of sheave 






'lameter of cable 




in inches 


Max 


. load in lbs 


1 

2 




20 




1,100 


9 
16 




22 




1,350 


5 

8 




25 




1,700 


3 

4 




35 




2,500 


7 
8 




45 




3,200 


1 




55 




4,000 



For freight elevators the above loads may be increased 25 per 
cent. 

Never less than four (4) hoisting cables are installed on an hy- 
draulic passenger elevator or on a worm-geared traction machine. 

Six cables are used on the gearless type of machine and the same 
number on the drum machine. In the latter case two are for 
hoisting, two for car counterweight, and two for the back drum 
weight. 

To determine the load on the hoisting ropes of a drum-type 
electric elevator, the maximum load is added to the estimated 
weight of car and safety device, and from this total the car counter- 
weight (which will be about two-thirds of the weight of safety 
plank and car) is deducted. 

Under normal conditions, in Federal buildings, the car and 
safety will weigh about 3200 pounds, and the maximum load 2200 
pounds; the pull on the ropes will then be (3200 plus 2200) — 
2200 equals 3200 pounds, which will be safe for two f-inch 
ropes. 



ELEVATORS .. 249 

To ascertain the weight of the drum counterbalance one-third 
of the weight of the car and safety is added to one-third of the 
load. 

A car counterweight is always provided unless car is very small 
and speed does not exceed 200 feet per minute. 

The cars for cable-operated hydraulic elevators are counter- 
weighted up to within 600 or 800 pounds of the weight of car for 
speeds up to 400 feet per minute. In the low-rise hydraulic 
plunger elevators w^ith speeds up to 50 feet per minute the counter- 
weights are within 500 pounds of the weight of the car and plunger, 
and for 100 feet per minute within 800 to 1000 pounds of the 
weight of the car and plunger. The average weight of a low-rise 
plunger with a 6-foot x 6-foot car is about 2000 pounds. 

Where the car travel exceeds 90 feet, a chain counterbalance 
is installed to offset the weight of cables. A braided cotton rope 
is threaded through the links of chain to reduce noise, or the 
chain is covered with canvas sewed on and painted. 

Two f-inch steel hoisting cables are generally used for electric 
dumb-waiters and usually one f-inch counterweight cable. The 
operating rope on a hand-power elevator is Russian hemp, 3 J 
inches in circumference. The hoisting ropes on hand-power ele- 
vators are iron. 

Tanks, pumps, etc. Compression tanks should not be made 
over 6 feet in diameter. The surge tank should be made of the 
same capacity as the compression tank. A vacuum valve should 
be placed on all pressure tanks. 

In proportioning a system for Federal buildings, especially 
where a small motor-driven pump is to be installed, a large tank 
and a small pump are used. The large compression tank re- 
duces the frequency of starts of the pump to a minimum and en- 
ables a few trips to be made with pump out of service. The 
compression and discharge tanks are made not less than twelve 
times the capacity of the cylinder or cylinders in small installa- 
tions, and between eight and ten times the capacity of all cylin- 
ders in large installations. 

The resultant pressure with pump out of service and tank up 
to maximum normal pressure, after drawing a given quantity of 
water, is calculated on the basis of Mariott's law. Assume a 
tank of 1000 gallons capacity, containing 600 gallons of water 



250 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

and 400 gallons of air and that the pressure in tank is 100 pounds 
and we desire to withdraw 80 gallons and determine the resultant 
pressure. The absolute pressure at start is 100 plus 15 equals 
115 pounds, and the amount of air is 400 gallons; then multiply 
400 by 115 and divide by 480, and from the result deduct 15 
pounds which will give the resulting pressure in tank. 

When the hydraulic elevators are scattered, an auxiliary com- 
pression tank is placed near each group of elevators. This prac- 
tice is strongly recommended by the leading elevator companies. 

When an hydraulic plunger elevator is operated by city water- 
pressure direct, and the street pressure is only about 50 to 
60 pounds a large steel reservoir is placed near the operating 
valve. 

Pumps for passenger and important freight service are so pro- 
portioned that they will restore to the pressure system the quan- 
tity of water used by the elevators during the period of a round 
trip, which in Federal buildings is assumed to be not less than 
one minute nor more than two minutes. 

Where the steam pressure generated in the building is 100 
pounds and over, it is the practice to install compound steam 
pumps. In very large jobs, three pumps are used, two large 
enough to handle the maximum travel and one in reserve. Ten 
per cent is allowed in all pump calculations for slip. When two 
pumps must be used, each one is made capable of maintaining the 
schedule plus 10 per cent. When three pumps are used and two 
are in service, the pressure governor of one is set about 20 pounds 
lower than the other so that the second pump comes into service 
only in case of excessive demand. 

Where eight (8) hydraulic elevators, or more, are installed and 
the pumping duty exceeds 500 gallons per minute for each pump, 
the high-duty fly-wheel pump or the triple-expansion duplex pump 
is used, if steam pressure is not lower than 135 pounds. One 
high-duty pump may be installed for day load and a smaller com- 
pound pump or pumps for reserve and night load. In the .unim- 
portant pumping installations, say for one mail and one freight 
lift, the total pump capacity per minute is made equal to the 
total hydraulic plunger disfclacjement and a triplex pump is se- 
lected to supply that amount of water at 30 revolutions per 
minute. 



ELEVATORS 251 

The operating valves for short-rise low speed direct plunger 
lifts usually vary in size from 2\ inches to 4 inches, depending 
upon the water pressure and speed of the lift. In each case the 
area through the valve is equal to the corresponding size of pipe. 
The size of the valve largely governs the speed of the lift; and it 
is desirable to install valves and piping of such size that the ve- 
locity of water through them will be about 10 feet per second, 
except where the pressure is low or water is taken from city water- 
mains direct, in which case a speed of 5 or 6 feet per second should 
not be exceeded. Under no conditions should a speed of 14 feet 
per second be exceeded in the supply of piping. 

In calculating plungers for standard hydraulic elevators, the 
total loss of pressure between the elevator pressure tank and the 
cylinder is assumed to be 15 pounds per square inch, provided 
the elevator is located reasonably close to the pressure tank. 

The standard sizes of plunger for direct hydraulic plunger lifts 
used are as follows: 



Inches 


Inches 


Inches 


Inches 


Inches 


^ 


6| 


8* 


10| 


12 


5£ 


7| 


n 


11 


12| 



The cylinders are usually lj inches larger inside diameter than 
the plunger; and the cylinder casing is 5 inches larger inside than 
the plunger diameter. 

In estimating the size of cylinders for the old style pushing and 
pulling type of hydraulic elevators, the following efficiencies are 
used. 

Ratio of 

gearing. .3:1 4:1 5:1 6:1 7:1 8:1 9:1 10:1 12:1 

Approxi- 
mate ef- 
ficiency.. 0.85 0.80 0.75 0.70 0.68 0.65 0.62 0.60 0.55 

These efficiencies, however, vary somewhat with the size of the 
cylinder and condition under which they are installed. 

The efficiency of a direct hydraulic plunger lift is usually taken 
at about 90 per cent when compensating counterbalance cables are 
used, and the same efficiency may be assumed when the ordinary 
counterbalance ropes only are installed if it be remembered in 



252 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

the calculation that the overbalance must be about 500 pounds 
plus the weight of 1 foot of the plunger. 

The following are examples of small direct plunger hydraulic 
lift plants which are giving satisfaction in Federal buildings: 

1. Two direct-plunger hydraulic lifts with platform 6 feet x 
6 feet, counterweighted to within 500 pounds of weight of plat- 
form and plunger; lift 23 feet 9 inches; water pressure in tank 
100 pounds; speed of lifts 50 feet per minute; maximum live load 
to be lifted, 2000 pounds; efficiency of lift taken at 90 per cent; loss 

, . , , r , 1K , (2000+500) X0.9 
m pressure from tank to cylinder, 15 pounds: — — = 

area of plunger, 27 square inches. Area of a plunger 6 J inches in 
diameter is 33 square inches; plunger displacement 33 square 
inches area x 23 feet 9 inches long equals 41 gallons per trip; 
compression tank 5 feet x 12 feet long equals 1800 gallons; dis- 
charge tank 6 feet wide x 8 feet long x 5 feet deep, equals 1800 
gallons capacity. Ratio tank capacity to total cylinder displace- 
ment, 22:1, two pumps each capable of discharging 40 gallons per 
minute against 100 pounds; motor horse-power equals 5 each, 
ratio of total pump displacement to total cylinder displacement 
in this case, 100 per cent. 

2. One freight lift with plunger 10| inch diameter and 26 feet 
lift (not counterweighted). 

One mail lift with plunger 15-inch diameter and 15 feet 4 inches 
lift (not counterweighted). 

One registry lift with plunger 8|-inch diameter and 15 feet 4 
inches lift (not counterweighted). 

Total displacement of the three plungers equals 41 cubic feet; 
pressure in tank 100 pounds; tanks 5 feet diameter by 18 feet 
long, each containing 370 cubic feet; ratio of compression tank 
to total cylinder capacity, 9:1, two pumps each designed to deliver 
80 gallons per minute; ratio of total pump capacity to total 
plunger displacement, 1:1.9, horse-power of each pump motor: 

80 X 100 „ _ 10 
1700 X 2 " 10 - 

The following is an example of calculating an horizontal hy- 
draulic pushing type of elevator such as were formerly installed 
by the office: 



ELEVATORS 253 

Car floor 6 feet x 5 feet equals 30 square feet; maximum live 
load 30 x 75 equals 2250 pounds at speed of 200 feet per minute; 
schedule 1 minute; travel 64 feet; underbalance 800 pounds; 
maximum tank pressure, 100 pounds; loss of pressure in valve 
and pipes, 15 pounds; minimum pressure in elevator cylinder, 85 

pounds; geared 8 to 1 ; stroke 8 feet; load equals — — X 8 

0.65 

equals 37,500; cylinder equals — ^— — equals 441 square inches 

diameter of cylinder equals 24 inches; cylinder capacity, 190 gal- 
lons; pump, 190 plus 10 per cent equals 210 G.P.M. at 50 strokes 
per minute; a 1600-gallon compression tank and a surge tank of 
similar capacity is used. 

The following is a description of a large hydraulic plunger lift 
installation for a Federal building : 

Seven plunger elevators are to be installed, six of which are to 
have platforms 6 feet wide and 19 feet long and the seventh a 
platform 6 feet x 5 feet. The large elevators are to have a ca- 
pacity to lift 5000 pounds at an up-speed of 100 feet per minute, 
and a down-speed of 125 feet per minute. The capacity of the 
small lift is 1500 pounds at 125 feet per minute. The travel of 
the large machines is 32 feet 6 inches and of the small machine 
15 feet. 

The plungers for the large machines are 11 inches in diameter, 
and for the small elevator 7-inch diameter. 

The operating valve for the large machines is 4-inch diameter, 
and for the small machine 2|-inch diameter. The speed in supply 
pipes and valves is made 12 feet per second and the discharge pipe 
from each machine is one size larger than the supply pipe. 

Each elevator is provided with a piston valve operated by a 
hand rope and each machine has an automatic stop valve. 

The water pressure used is 150 pounds per square inch. 

There are two compression tanks, one located near the pumps 
and the other in a central location with respect to the elevator 
groups. The tank near pumps is 3000 gallons capacity, and the 
other one is 4500 gallons capacity. The tanks are tested to 300 
pounds pressure. 

Near the pumps is one main surge tank which is of the open 
type and of 6000 gallons capacity. 



254 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Three (3) pumps are installed each capable of discharging at 
not over 125 feet per minute piston speed 250 gallons of water per 
minute into the compression tanks at 150 pounds pressure. 

Two of the pumps will maintain a 2-minute schedule for all 
elevators with a liberal allowance for slip and leakage. 

Two railroad type of air compressors are used to maintain the 
air cushion in the compression tanks. 

All piping is standard black wr ought-iron and all fittings are 
extra-heavy 800 pounds test. Each of the large machines is pro- 
vided with a compensating counterbalance consisting of eight 
1-inch diameter steel cables. The small machine is not counter- 
balanced. The large machines are guided in the center as usual 
and the steel guides are made of 4-inch x 5-inch tee irons. 

The following is a brief specification for the standard tandem 
worm geared electric passenger elevator with direct current motor 
and full magnet control such as is installed by the office of the 
Supervising Architect: 

ELECTRIC PASSENGER ELEVATOR 

1. Hoistway. The hoistway for the electric passenger ele- 
vator will be provided, complete with enclosure and entrance 
doors, under another contract. 

2. Pit. A pit of 4 feet deep will be provided for elevator 
under another contract. 

3. Indicator. A first-class and approved mechanical indi- 
cator, complete with dials, etc., which will correctly show the 
position of car in hoistway, must be furnished and installed. 

4. Revolution counter. Contractor must install on elevator 
machine an approved device which will record the number of 
revolutions in one direction made by the drum of machine. 

5. Metal grating. A suitable metal grating constructed of 
2-inch pierced channels or lj by f-inch flat bars with spool or cor- 
rugated bar separators, capable of sustaining a load of 75 pounds 
per square foot, must be provided in hoistway immediately below 
the bottom of sheaves. 

6. Overhead supports. All overhead work is to be supported 
on an approved arrangement of steel beams furnished by this 
contractor; beams to be supported by the walls of the hoistway 
as shown. 



ELEVATORS 255 

7. Drip pans. Drip pans constructed of No. 26 United 
States standard gauge galvanized iron shall be provided under 
all bearings, to prevent any oil dripping down hoistway. 

8. Foundation. A concrete foundation not less than 3 feet 
deep and of proper size to receive the bedplate of machine must 
be provided, and anchor bolts of sufficient number, not less than 
J-inch diameter, with pipe sleeves and bottom plates, are to be 
built into the foundation. Top of foundation to be flush with 
floor. 

9. Guides. Car guides are to be cold-rolled or planed steel, 
of best quality, T section, not less than 4J by 3| inches, and 
must weight not less than 14 pounds per linear foot. 

10. Guides for counterweights shall be T section, not less than 
2f by 2 inches, and must weight not less than 7 pounds per linear 
foot. 

11. All guides shall be securely fastened in place with approved 
heavy pattern clamps, secured to walls or framing of hoistway. 
Brackets are to be used in connection with clamps wherever 
necessary. 

12. Where supports for car guides are more than 12 feet apart 
that portion of guide between such supports shall be stiffened 
with two 2| by 3 J inch angles, weighing not less than 4.9 pounds 
per foot, or one 7-inch channel, weighing not less than 9.50 pounds 
per lineal foot. 

13,. Ends of guides shall be tongued and grooved, forming 
matched joints, and where not reinforced shall be fitted with 
splice plates. 

14. Splice plates for car guides shall not be less than 12 inches 
long, secured to each guide with four f-inch bolts; plates for 
counterweight guides shall not be less than 9 inches long, se- 
cured to each guide with four J-inch bolts. 

15. Guides shall be erected perfectly plumb, and all shim- 
ming shall be done with metal. 

16. Winding machine. — Machine must have all parts made to 
standard dimensions, using templates, jigs, etc., to secure com- 
plete interchangeability in all machines of the same size made by 
this manufacturer. 

17. The proportion of all members shall be such that the 
maximum fiber stress under maximum duty specified shall not 
exceed the following values : 



256 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Cast iron, 2000 pounds per square inch. 
Gun iron, 3000 pounds per square inch. 
Bronze, 3000 pounds per square inch. 
Steel, 8000 pounds per square inch. 

18. Capacity and speed. Elevator must have the capacity to 
lift a live load of 2000 pounds, exclusive of weight of car and 
cables, at a minimum speed of 200 feet per minute and a maxi- 
mum load of 2400 pounds at reduced speed. 

19. A variation of 15 per cent above this speed is the maximum 
permissible under all conditions of load up or down. 

20. Travel. Machine must permit a car travel of 52 feet 8 
inches, more or less, from basement floor to fourth floor. 

21. Bedplate. Bedplate to be cast iron, in one piece, with 
stiffening ribs to accurately maintain alignment of parts secured 
thereto. Pads accurately planed or milled must be provided as 
seats for all parts secured to bedplate. Cap screws shall be used 
to secure parts to bedplate wherever possible. 

22. The use of brackets or other extensions bolted to bedplate 
to secure parts thereto will not be permitted. 

23. Bedplate shall preferably be provided with raised edges 
to prevent oil dripping off, and if not so provided the machine 
must be set in a pan not less than 2 inches deep, and constructed 
of No. 22 United States standard gauge galvanized steel with 
wired edges and thimbles around anchor bolts. 

24. Winding drum. Winding drum to be of cast iron, accu- 
rately turned and spirally grooved for cables. The grooves are 
to be of sufficient length to accommodate at least one turn of each 
hoisting and drum counterweight cable in addition to that required 
for the travel of the car. Cabled to be secured to drum by pass- 
ing same through drum face and clamping same inside of drum. 

25. Drum must be mounted between bearings, not overhung, 
and shall be secured to gear by bolts through flanges or by means 
of a flexible drive. Keying drum or gear to shaft must not be 
depended upon to do any driving of drum. Bearings for drum 
shaft shall be lined with antifriction metal provided with means 
for taking up wear and with continuous oiling devices, and shall 
be of such proportions that the maximum pressure in bearing 
shall not exceed 350 pounds per square inch of bearing surface. 



ELEVATORS 257 

26. Type of machine. Machine shall be of the duplex worm- 
gear type, with motor, brake, and drum mounted on a single 
self-contained base. 

27. Worms. Worms shall be right and left hand, cut from 
solid stock with shaft, and shall have a pitch diameter not less 
than 4 inches. No thrust bearings on worm shaft will be per- 
mitted. 

28. Gears. Gears shall have bronze rims. Intermeshing 
teeth shall be of spiral form, accurately cut, and meshing with 
minimum backlash. Worm path may be cut from center of spiral 
teeth or may be cut at one side, with a pitch circle sufficiently 
smaller than that of the spiral to prevent worm paths meshing, 
but must be cut from solid stock with spiral gear. 

29. Bronze shall be of such composition that gears will not 
show appreciable wear after one year's service. 

30. Worm wheels shall be of equal size and of such diameter 
relative to that of drum that the maximum pressure between 
worm and gear shall not exceed 1600 pounds per gear. 

31. Rims shall be secured onto cast-iron centers by turned or 
threaded bolts driven or screwed into reamed or tapped holes, 
with end of bolt headed over after being screwed up tight. Bolt 
holes through the joint between the rim and center will not be 
permitted. 

32. Gears shall be formed and fitted to standards to permit 
interchangeability. 

33. Gears must be so perfectly fitted that no appreciable vi- 
bration will be felt in car at any speed or load within the limits 
specified, and shall operate without appreciable noise. 

34. Gear cases. Cases for inclosing gears to be constructed of 
cast iron of ample strength arranged to hold a body of oil. Cen- 
ters of gear shafts and distance between centers of worm and gear 
shafts shall be nonadjustable, and shall be the same in all ma- 
chines of one size to permit interchangeability of gears. Gear 
cases shall be provided with manholes for inspection of gears and 
removal of worm and with stuffing box for worm shaft arranged 
to prevent rattling at all tensions of packing. 

35. Motor. Motor is to be wound for 220 volts direct current. 
Contractor must verify voltage before commencing work. It is 
to be of design adapted to elevator service, and must be capable 



258 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

of developing the required power and starting torque and of with- 
standing temporary overloads of at least 50 per cent and shocks 
occasioned by frequent starting under heavy loads. Bearings to 
be of the self-oiling type. Motor must be designed to operate 
practically without noise. 

36. Compounding. The motor must be compound wound, to 
give a high starting torque. 

37. Field coils. Field coils must be form wound and so se- 
cured that they may be readly removed without unwinding. 

38. Armature. Armature must have slotted core, with wind- 
ings thoroughly insulated and secured firmly in place. It must 
be balanced both mechanically and electrically and be well ven- 
tilated and easily removable. The end of armature shaft shall 
be provided with a square or slotted opening to receive crank for 
turning machine by hand. 

39. Commutator. Commutator to be of drop-forged or hard- 
drawn copper of highest conductivity, insulated with mica or 
micanite of even thickness and proper hardness to insure uniform 
wear, and must run free from sparking or flashing at the brushes 
at any load up to specified full load or during change of load. It 
must have ample bearing surface and radial depth for wear. 

40. Brushes. Brushes to be of carbon of such cross-sectional 
area as will not cause sparking, burning, or blackening of commu- 
tator at load specified. 

41. Brush holders. Brush holders to be of such design that 
no chattering will result from continuous use. Collective adjust- 
ment of brushes to be made by means of rocker, and individual 
brush tension is to be maintained by a spring. If the motor is of 
the interpole type, the rocker arms may be omitted. 

42. Insulation. The frame of machine must have an insula- 
tion resistance from the field coils, armature windings, and brushes 
of not less than 1 megohm. Motor must be capable of stand- 
ing a breakdown test of 1500 volts alternating current for one 
minute. 

43. Heating effect. Motor is to be run continuously at full 
load for two hours, and at the expiration of that time the tempera- 
ture of the armature and fields shall not exceed 50° C. and of the 
commutator 55° C. above the temperature of the surrounding at- 
mosphere. Temperature to be measured by thermometers 



ELEVATORS 259 

shielded by cotton waste in a manner approved by department's 
agent. 

44. Efficiency. Bidders are required to state in their proposal 
the rated horsepower output of the motors, the efficiency of which 
must not be less than follows: One-half load, 82 per cent, and 
full load, 88 per cent. If shunt field resistance is used in making 
shop test, it is to be understood that the losses in the field rheostat 
will not be included in calculating motor losses. 

45. Shop test. The efficiency, heating effect, insulation re- 
sistance, etc., of motor shall be determined by actual test in the 
presence of department's authorized agent, who shall determine 
the test conditions. 

46. Efficiency test shall be by stray power method. 

47. The test to be made at the shop where motor is constructed 
and to begin within 10 days after receipt of notice from contract- 
ors of their readiness to commence test, and to be at the expense of 
the contractors, except traveling and other necessary expenses of 
the department's agent. 

48. Delayed tests to be as hereinbefore specified. 

49. The Supervising Architect reserves the right to waive the 
shop test and require contractor to submit test sheets in triplicate 
for approval, it being understood that those portions not waived 
shall be exacted when the apparatus is installed, if not performed 
at the shop as specified above. 

50. Brake. Brake pulley is preferably to be the face of coup- 
ling between armature and worm shafts. In any event the brake 
pulley must be shrunk or keyed direct to worm shaft. 

51. Brake leather must be in two sections, either of which is 
a complete brake and will be effective on failure of the other half. 

52. The area of the brake leather shall not be less than 50 
square inches per shoe. Brake shoes to be applied by gravity or 
a spring, and in either case the pressure must be adjustable. 

53. Brake to be released by an electromagnet. Magnet must 
be fitted with a device to cut resistance in series with brake coil 
when solenoid core is fully lifted, or must be compound wound 
with series coil in series with motor series field. 

54. The circuit of brake magnet must be opened by the sev- 
eral safety devices so as to apply the brake at both limits of travel ; 
when car attains excessive speed; when car is checked in hoistway 



260 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

while descending; when operator removes hand from car-switch 
lever or brings it to stop position; when the emergency switch is 
opened; and on failure of current. 

55. Finish of machine. The machine is to be filled, rubbed 
down, and painted one coat before leaving the shop. When 
erected and ready for operation it is to be finished with one addi- 
tional coat of paint, of tint approved by the custodian, and one 
coat of varnish. All other new ironwork in connection with ele- 
vator, except ornamental cage, is to be painted two coats best 
quality black asphaltum paint. 

56. Wrenches. A complete set of wrenches for elevator ma- 
chinery is to be furnished and mounted in a suitable hardwood 
frame, located where directed by the custodian. 

57. Type of control. The elevator control is to be of the full 
magnet type, consisting of an operating switch in car electrically 
connected with controller magnets which make the various con- 
nections governing direction, acceleration, and speed. 

58. All switches are to be of the butt or butt and wipe type, 
actuated by solenoids direct; no long-stroke solenoids, dashpots 
racks, pinions, pilot motors, cams, or sliding contacts (except in 
car switch) will be permitted. 

59. Controller panel or panels shall consist of first quality black 
slate treated to prevent absorption of moisture and of ample size 
and not less than lj inches thick, securely fastened to an angle- 
iron frame. Switches to be mounted on the front of the board and 
resistances and connections on the back. Solenoids either front 
or back. All parts to be readily accessible for renewal and ad- 
justment. 

60. Controller must contain the following appliances, which 
must perform the functions specified : 

61. Potential switch. A solenoid-operated double-pole switch 
which, when open, will disconnect motor circuit must be pro- 
vided. This switch may be operated by the car switch but must 
be opened by the several safeties hereinafter specified. 

62. Direction switches. Direction switches must -make and 
break circuit and reverse motor under control of operator. These 
switches must be plainly marked "Up" and "Down;" must be 
interlocked mechanically or electrically. They must be provided 
with magnetic blowouts. 



ELEVATORS 261 

63. Brake circuit to be closed by a double-pole switch coinci- 
dent with operation of direction switches. 

64. Accelerating switches. Accelerating switches shall cut out 
resistance in series with armature by successive steps, so as to 
give a gradual acceleration of car, and limit the maximum accel- 
erating current to 35 per cent in excess of the speed-load running 
current, with controller set for five-second acceleration. The 
closing of these switches may be controlled by counterelectromo- 
tive force, current strength or fall of potential through resistance. 

65. The switch which cuts out series field shall be operated 
independent of a time element of such duration as would permit 
the reversal of series field. 

66. Controller must permit of slow-down before making stop 
and must also produce a dynamic braking action on stopping. 

67. Controller must prevent the admission of more current 
than is necessary to lift the maximum load. In event that a 
relay is necessary, same must be self-restoring. 

68. All contacts shall have brass or copper for one face and 
carbon for the other with cushion springs, or shall have laminated 
copper main contact with auxiliary carbon break. Contacts 
shall be of such proportions that the maximum current density 
shall not exceed 100 amperes per square inch of contact area. 

69. In carbon-to-copper contacts are used the contact cutting 
out series field must be arranged to cut resistance in series with 
field when same is cut out, or a graphite block must be used in 
lieu of carbon. 

70. Acceleration and dynamic resistance shall be first-quality 
cast iron or wire, insulated with mica and mounted to give con- 
tact pressure between grids at all temperatures. Resistances in 
connection with shunt field, solenoids, etc., shall be wound on 
noncombustible bases and mounted so as to be readily removed. 

71. If the shunt field of motor is left in circuit when machine 
is at rest, resistance must be inserted in series with same to limit 
the current consumed to not exceeding 1.5 per cent of full-load 
current of motor. 

72. All wiring on controller shall be neatly arranged and se- 
curely fastened in place; must be readily accessible and easily 
traced. A complete wiring diagram must be furnished to the 
custodian. 



262 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

73. All parts of controller must be rugged in design to with- 
stand hard usage of elevator service. 

74. Guide grips. Guide grips of first-class design, which be- 
come operative whenever the maximum speed limit is exceeded 
in descending, must be provided on car. Guide grips shall have 
not less than J-inch clearance. 

75. Guide grips must be operated by an endless standard iron 
hoisting rope passing through a clamping device, controlled by a 
centrifugal governor at top of hoistway and around a weighted 
idler at bottom of hoistway. A phosphor-bronze cable passing 
around a drum under car must be attached to the iron rope in 
such a manner that when rope is clamped drum is to revolve and 
operate the guide grips by means of screws. 

76. In lieu of above the bronze cable may pass around a block- 
and-fall device under car, which, when rope is clamped, will operate 
the guide grips. 

77. The guide grips shall be tested by dropping car with a 
net load on the platform equal to two-thirds the maximum load 
specified. 

78. The total distance traveled by the car after the rope has 
been cut shall be not less than 6 feet nor more than 9 feet. Car 
must not be out of level, when grips have set, more than J inch in 
each foot of length between guide rails. Governor must be set 
for 140 per cent of contract speed. 

79. Provision must be made to release guide grips without go- 
ing under the car. 

80. The test is to be made before connecting the cables. It is 
to be made at the building in the presence of the department's 
representative, who will advise the department when a satisfac- 
tory test has been made. 

81. Automatic limit switches. Switches operated from drum 
shaft must be provided to slow down and stop car at upper and 
lower landings independent of operator. The variation in point 
of stopping with no load and full load on car shall not exceed 6 
inches. 

82. Ultimate limits. Limit switches are to be provided in 
hoistway which open potential switch when car travel is exceeded 
in either direction. These limits shall be located at least 6 inches 
beyond the maximum travel at which automatic limits stop car. 



ELEVATORS 263 

83. All limit switches are to be butt contact of ample size. If 
limits break main-line circuits, current densities shall not exceed 
twice that specified for controller contacts. 

84. Speed governor. A centrifugal governor must be provided 
to cut off the motor current at determined maximum speed. If 
this governor is used to operate the guide grips, it must perform 
both operations independently; the motor current to be cut off 
before the speed at which the guide grips operate has been at- 
tained. 

85. Slack-cable switch. A safety switch must be provided for 
cutting off current if for any reason the car is suddenly checked 
in hoistway while descending or upon the breaking of one or both 
of the hoisting or back-drum cables. 

86. Car-switch stop. The car switch must be provided with 
an attachment which will bring the switch to stop position if for 
any reason the operator removes his hand from the switch lever. 

87. Emergency switch. A switch is to be provided in car 
which may be used by operator to open the controller circuit 
through the potential switch in case of accident. 

88. Cable separate from and similar in construction to the 
car-switch cable must connect the emergency switch to the con- 
troller. 

89. Buffers. Two extra-heavy spring buffers supported on 
substantial steel framing are to be provided for car and two for 
counterweights. 

90. Sheaves. All sheaves are to be cast iron of as large diame- 
ter as conditions will permit, grooved to accommodate the size of 
cables used. Separate sheaves for drum and car counterweight 
cables shall be provided where space permits. 

91. Wherever space permits, all sheaves shall be pressed onto 
sheel shafts. Sheaves turning but not sliding on shafts shall be 
fitted with bronze bushings. Sheaves turning and sliding need 
not have bushings. 

92. Bearings for sheaves shall be lined with antifriction metal, 
shall be self-aligning, shall be provided with grease cups, and 
shall be so proportioned that the maximum bearing pressure shall 
not exceed 350 pounds per square inch. 

93. Cables. The elevator is to be provided with 6 cables — 2 
hoisting cables, 2 drum counterweight cables, and 2 car counter- 



264 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

weight cables. The cables connected to drum are to be of such 
length that there will be at least one complete turn of each on the 
drum at any position of the car. 

94. All cables are to be best Swedish iron, standard hoisting 
rope, f-inch diameter, consisting of 6 strands, 19 wires each, wound 
about a hemp core or center. 

95. Cables to be secured to car and counterweight frames 
with thimble shackles. 

96. Counterweights. The car is to be counterweighted di- 
rectly. The load is to be partially counterweighted at back of 
drum. 

97. The total overweight must not exceed one-third the maxi- 
mum load. 

98. The weights are to be secured to the frames in such a 
manner that they can not be jarred out or released by the spread- 
ing of the rods connecting the top and bottom of counterweight 
frame. 

99. Car. Elevator car shall be as large as hoistway will per- 
mit. Sling and safety plank shall be constructed of wrought- 
steel plates, steel castings, and structural shapes. No iron cast- 
ing to be used except for lift plate. 

100. Car platform shall be securely framed and braced and is 
to have a maple floor 1} inches thick, provided with best quality 
compressed-cork flooring not less than \ inch thick, securely 
fastened in place. Entrance to car to be provided with check- 
ered brass threshold flush with cork. 

101. Guide shoes shall be fitted with removable wearing gibs; 
must be mounted to permit self-alignment and be provided with 
spring take-up for side play. 

102. Lubricators are to be provided for the main and counter- 
weight rails. They are to be of the oil type, the oil being fed from 
a reservoir through wipers or wicks by capillary attraction. The 
oil is to be so applied to the rails as to give an even distribution 
upon the face and two sides. The wipers are to be held against 
the rails by spring pressure so that the oil may be applied evenly 
through the entire travel of the car. 

103. The ornamental cage is to be constructed of wrought iron 
or steel. The top is to be panelwork, while the sides are to be 
made of sheet metal and wire glass to match the hoistway entrance 



ELEVATORS 265 

doors. The car finish is to be dead black. Cage shall have re- 
movable panel in top for emergency exit and at sides for access 
to hoistway limits. 

104. The ornamental cage to cost not less than $500. 

105. Annunciator. An electric annunciator of the drop type, 
with metal case finished to harmonize with the car, is to be placed 
in car. Annunciator is to be connected to a battery and to push 
buttons at each landing. 

106. Annunciator wiring in the hoistway is to be run in rigid 
iron conduit. 

107. Light fixtures. The car is to have an electric fixture of 
simple design finished to match inclosure, fitted with one Edison- 
base keyless socket and 8-inch-diameter prismatic reflector pro- 
perly connected by means of all necessary wires, etc., to the elec- 
tric wiring of the building. 

108. A flush snap switch is to be mounted in car for control 
of the electric light. 

109. Tablet. This contractor will be required to furnish and 
install near elevator machine a black slate tablet, treated to pre- 
vent absorption of moisture, not less than 1} inches thick, or, if 
mounted with controller board of same thickness, having mounted 
thereon one double-pole single-break knife switch of ample ca- 
pacity, one to 300 volt direct-current voltmeter with switch for 
disconnecting same, and one direct-current ammeter of proper 
range to indicate the maximum starting current. Ammeter shall 
be connected through a double-pole and a single-pole single-throw 
switch, to permit ammeter to be thrown out of circuit without 
interrupting the circuit. 

110. Instruments shall be of the D'Arsonval pattern, dead 
beat in action, inclosed in metal cases arranged for surface mount- 
ing on switchboard. 

111. All connections are to be made on back of board by copper 
bars and copper lugs for the reception of conductors. 

112. Connections. All connections from power service to tab- 
let, elevator, etc., must be made by this contractor. 

113. All conductors are to be run in steel conduit terminating 
in approved conduit fittings, except such connections between 
controller and motor as may be so short as to be self-supporting, 
and these must be fully protected from abrasion or other mechani- 
cal injury. 



266 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

114. Conductors inside the building must be rubber-covered, 
well-tinned, soft-drawn copper of highest conductivity, made 
in strict accordance with the National Electrical Code, and must 
have a distinctive marking of the maker. 

115. All conductors, No. 8 Brown & Sharpe gauge and larger, 
are to be stranded and connections made by soldering wires in 
cup lugs. No joints or splices will be permitted in feeders except 
at outlets. 

116. Wiring system must test free from short circuits or grounds 
and the insulation resistance between conductors and between 
conductors and ground must not be less than 1 megohm. 

117. Where size of conductors is not given, the capacity must 
be such that the maximum current carried will not exceed the 
limits prescribed by the National Electrical Code, and drop in 
potential must not exceed 3 volts at full load. 

118. Safety interlock. Bidders must name in proposal the 
amount for which they will equip the elevator with a first-class 
safety device which will prevent the operation of the elevator while 
any inclosure door is open. Device must render it impossible to 
move elevator by manually closing direction switches on elevator 
control board while any hoistway door is open. 

119. An emergency switch must be provided in the car to per- 
mit the operation of the elevator while the hoistway door is open. 
This switch shall be inclosed in metal case, with thin glass in 
door to be easily broken when necessary. Door shall be provided 
with a key to permit insertion of new glass by authorized person. 

120. Name of manufacturer of safety interlock must be sub- 
mitted by contractor. 

121. Automatic door-operating device. Bidders shall name in 
proposal sheet the amount for which they will equip the elevator 
hoistway doors with an approved pneumatic operating device 
and automatic interlock. 

122. The operating devices to be of the nonadjustable type, 
without packing glands, arranged to cushion the doors on both 
the opening and closing motions, and are to operate the door 
rapidly and noiselessly. 

123. Operating devices are to be arranged so that the doors 
will automatically close and lock in the event of the elevator car 
leaving the floor while the door is open, and are to be provided 



ELEVATORS 267 

with mechanical locks so that doors can not be opened from the 
outside even though the air pressure should be interrupted. Op- 
erating device on the basement door to be so arranged that it 
can be opened from the outside by an authorized person only. 

124. Furnish and install an automatic lubrication system that 
will properly lubricate all valves and pistons. 

125. Furnish and install all necessary mechanical connections 
between operating devices and doors, between various sections 
of doors, and all controlling mechanism, so arranged that the op- 
erator will have full control of doors while car is adjacent to floor. 

126. Furnish and install on each inclosure door an interlocking 
switch with necessary conduit and wiring connected to elevator 
control circuit in such a manner as to prevent starting car while 
any inclosure door is open (more than 4 inches), and so arranged 
that the opening of any door while the car is in motion will stop 
the car. Interlock to be so arranged as to prevent moving car 
by manually closing direction switches while any hoistway door 
is open. 

127. An emergency switch to be installed in car to cut out 
door switch circuit. This switch to be placed in a suitable metal 
box with locked glass cover, making it necessary to break the 
glass cover before switch can be operated. 

128. Air compressor. Furnish and install one electrically driven 
air compressor of the intermittent type with a capacity of not 
less than 10 cubic feet of free air per minute. 

129. Compressor to have not less than two cylinders, cast in- 
tegral with crank case, made of fine grained cast iron. Interior 
of cylinders are to be accurately machined and smoothly finished. 

130. Pistons to be of trunk type, carefully ground to fit bore 
of cylinders. Each piston to be provided with spring piston rings. 
Wrist pins are to be of hardened steel, thoroughly tempered and 
perfectly ground. They are to be pressed into position in piston 
and rigidly secured by set screws. 

131. Connecting rods to be cast iron or steel of such form as to 
combine strength and rigidity without excessive weight. They 
are to have renewable- phosphor-bronze bushings at wrist-pin end 
and babbitt-lined split bearings at crank-shaft end. 

132. Bearings. Crank-shaft bearings are to be provided with 
phosphor-bronze bushings and have liners to take up wear. 



268 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

133. Crank shafts to be forged or cast open-hearth steel, ac- 
curately machined to receive connecting rods, gears, and main 
bearings. 

134. Gear to be herringbone pattern made of two steel castings 
riveted together after cutting gears. Gear must be securely- 
keyed to crank shaft. 

135. Valve head to be cast iron secured to ends of cylinders. 
Head to contain chambers to receive suction and discharge valves. 
Valves to be machined from solid steel and are to be guided by 
vertical plugs into same. Valves are to seat by gravity without 
the use of springs. 

136. Suction valves to be actualized by the automatic unloader 
hereinafter specified. 

137. Motor. Motor to be wound for 220 volts, direct current. 
Motor to be of ample power to perform the work required and 
capable of withstanding overloads of 50 per cent. 

138. The insulation resistance between conductors and frame 
of motor must not be less than one megohm and the insulation 
must have a dielectric strength to withstand 1500 volts alternat- 
ing current for one minute. 

139. The motor must be capable of carrying full rated load as 
specified for a period of one-half hour continuous run with a rise 
in temperature of windings and core not exceeding 50°C. above 
the temperature of the surrounding atmosphere. Temperature 
to be measured by thermometers shielded by cotton waste. 

140. Switch. Furnish and mount on tablet containing elevator 
switches and instruments one 30-ampere double-pole single-throw 
knife switch with inclosed indicating fuses for controlling air 
compressor. Make necessary electrical connections between ele- 
vator feeders, switch, governor, and motor. 

141. All conductors are to be run in steel conduit terminating 
in approved condulet-type fittings, except such connections as 
may be so short as to be self-supporting, and these must be 
fully protected from abrasion or other mechanical injury. Con- 
ductors must be rubber covered, well tinned, soft drawn copper of 
highest conductivity, made in strict accordance with the National 
Electrical Code, and must have a distinct marking of the maker. 

142. All conductors No. 8 Brown & Sharpe gauge and larger 
are to be stranded and connections made by soldering wires in 



ELEVATORS 269 

cup lugs. No joints or splices will be permitted in feeders except 
at outlets. 

143. Wiring system must test free from short circuits or ground 
and the insulation resistance between conductors and between 
conductors and ground must not be less than 1 megohm. 

144. Where size of conductors is not given the capacity must 
be such that the maximum current carried will not exceed the 
limits prescribed by the National Electrical Code. 

145. Governor. Furnish and connect an automatic pressure 
governor which will start motor when air pressure in storage 
tank falls to 30 pounds and stop motor when pressure rises to 
60 pounds. 

146. Storage tank. Furnish and erect on suitable foundation 
of brick or concrete one galvanized-steel storage tank 2 feet di- 
ameter and 6 feet high tested to 100 pounds pressure. 

147. Provide 1-inch safety valve and J-inch drain on this tank. 

148. Provide a pressure-reducing valve on discharge pipe from 
storage tank set to maintain 30 pounds pressure on lines to door- 
operating devices. Provide a 5-inch dial pressure gauge on each 
side of pressure reducer. 

149. All necessary connections between door-operating devices, 
tanks, and compressors to be furnished. 

150. All pipe to be standard weight galvanized wrought iron 
or mild steel, all fittings to be standard weight galvanized malleable 
iron beaded fittings. 

151. Provide all necessary valves and stopcocks to permit op- 
eration of system and cutting out of any door-operating device 
without interfering with the proper operation of the remainder of 
the system. 

152. The name of manufacturer of automatic cloor-operating 
device to be submitted by contractor. 

ALTERNATING CURRENT ELEVATORS 

If the current available is alternating the specification for the 
elevator is changed from that for direct current as follows, the 
paragraph numbers referring to the paragraphs in the direct cur- 
rent specification: 

Paragraphs 1 to 34 inclusive same as direct current. 



270 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Paragraphs 35 to 84 inclusive substitute the following : 
35-41. Motor. Motor is to be of the induction type, wound 
for 220 volts, 3-phase, 60-cycle, alternating current, and provided 
with collector rings for connecting the rotor to the required ex- 
ternal starting resistance. The motor shall be a of design adapted 
to elevator service and shall be capable of developing a high start- 
ing torque with proper starting resistance, with a high power 
factor at starting. Motor must be capable of withstanding an 
overload of 50 per cent and shocks occasioned by frequent start- 
ing under heavy loads. All parts are to be properly proportioned 
for strength and wear and the bearings are to be of the self-oiling 
type. 

42. The insulation resistance between conductors and frame 
of motor must not be less than 1 megohm, and the insulation 
must have a dielectric strength to withstand 1500 volts alternat- 
ing current for one minute. 

43. The motor must be capable of carrying full rated load as 
specified for a period of two hours' continuous run, with a rise 
in temperature of windings and core not exceeding 50°C. above 
the temperature of the surrounding atmosphere. Temperature to 
be measured by thermometers shielded by cotton waste. 

44. Contractor is required to state in list of material the rated 
horsepower output of the motor and the guaranteed efficiency and 
power factor when running at J, f , full, and 1J load output. 

45^6. Shop test. The efficiency, power factor, heating effect, 
insulation resistance, and dielectric strength shall be determined 
by actual test in the presence of department's authorized agent, 
who shall determine the test conditions. 

47. The test to be made at the shop where motor is constructed, 
and to begin within 10 days after receipt of notice from contractor 
of their readiness to commence test; and to be at the expense of 
the contractors, except traveling and other necessary expenses of 
the department's agent. 

48. Delayed tests to be as hereinbefore specified. 

49. The Supervising Architect reserves the right to waive the 
shop test and require contractor to submit test sheets in tripli- 
cate for approval, it being understood that those portions not 
waived shall be exacted when the apparatus is installed, if not 
performed at the shop as specified above. 



ELEVATORS 271 

50. Brake. Brake pulley is preferably to be the face of coup- 
ling between armature and worm shafts. In any event the brake 
pulley must be shrunk or keyed direct to worm shaft. 

51. Brake leather must be in two sections, either of which 
is a complete brake, and will be effective on failure of the other 
half. 

52. The area of the brake leather shall not be less than 80 
square inches per shoe. Brake shoes to be applied by gravity or 
a spring and in either case the pressure must be adjustable. 

53-54. Brake to be released by an electromagnet. Magnet 
shall preferably be of the polyphase type, and in any case must 
be so designed as to prevent any disagreeable humming noise 
when in operation. The circuit of brake magnet must be opened 
by the several safety devices, so as to apply the brake at both 
limits of travel; when car attains excessive speed; when car is 
checked in hoistway while descending; when operator releases car 
switch lever or brings it to stop position ; when emergency switch 
is opened, and on failure of current. 

55. Finish of machine. The machine is to be filled, rubbed 
down, and painted one coat before leaving the shop. When 
erected and ready for operation it is to be finished with one addi- 
tional coat of paint of tint approved by superintendent and one 
coat of varnish. All other new ironwork in connection with ele- 
vator is to be painted two coats best quality black asphaltum 
paint. 

56. Wrenches. A complete set of wrenches for elevator ma- 
chinery is to be furnished and mounted in a suitable hardwood 
frame, located where directed by the superintendent. 

57. Type of control. The elevator control is to be of the full 
magnet type, consisting of an operating switch in car electrically 
connected with controller magnets which make the various con- 
nections governing direction, acceleration, and speed. 

58. All switches to be butt contact and all except relays or 
pilot contacts are to be of the clapper type. Dashpots will be 
permitted in connection with car switch or to operate pilot switches 
on control board, and if used must be of the inverted type to 
avoid collection of dust. No racks, pinions, cams, or other me- 
chanical appliances to operate any of the main direction or ac- 
celerating switches will be permitted. 



272 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

58 a. All solenoids shall be operated from the power circuit 
direct, without the use of rotary or stationary transformers and 
they must be practically noiseless in operation. 

59. Controller panel or panels shall consist of first quality 
black slate treated to prevent absorption of moisture and of 
ample size, and not less than 1 J inches thick, securely fastened to 
an angle-iron frame. Switches to be mounted on the front of 
the board and resistances and connections on the back. Solenoids 
either front or back. All parts to be readily accessible for re- 
newal and adjustment. 

60. Controller must contain the following appliances, which 
must perform the functions specified : 

61. Potential switch. A solenoid-operated double-pole switch 
which, when open, will disconnect all phases of motor circuit 
and open the circuit of brake magnet must be provided. This 
switch may be operated by the car switch and must be opened by 
the several safeties hereinafter specified. 

62. Direction switches. Direction switches must make and 
break circuit and reverse motor under control of operator. These 
switches must be plainly marked "Up" and "Down;" must be 
interlocked mechanically or electrically. 

62 a. The circuits energizing solenoids must be so connected 
that in the event that any one wire of supply circuit is opened 
either the direction or the potential switch will be opened and the 
brake applied independent of the position of the car switch. 

63. Brake circuit to be closed coincident with operation of di- 
rection switches. 

64. Accelerating switches. Accelerating switches shall cut out 
resistance in series with the rotor circuits by successive steps and 
short-circuit rotor at full speed. The closing of these switches 
may be controlled by current strength, by solenoid and dashpot, 
or by gravity and dashpot. 

65-67. Controller must prevent the closing of direction 
switches unless all resistance is in series with rotor. 

68-69. All contacts shall have brass or copper for one face 
and a carbon block with cushion springs for the other, or shall 
have copper main contact. Contacts shall be of such proportions 
that the maximum current density shall not exceed 100 amperes 
per square inch of contact area. 



ELEVATORS 273 

70-71. Rotor resistance shall be constructed of cast iron, in- 
sulated with mica, and mounted to give constant contact pressure 
at all temperatures. Resistances in connection with solenoids, 
etc., shall be wound on noncombustible bases and mounted so as 
to be readily removed. 

72. All wiring on controller shall be neatly arranged and se- 
curely fastened in place; must be readily accessible and easily 
traced. A complete wiring diagram must be furnished to the 
superintendent. 

73. All parts of controller must be rugged in design to with- 
stand hard usage of elevator service. 

74. Guide grips. Guide grips of first-class design, which be- 
come operative whenever the maximum speed limit is exceeded 
in descending, must be provided on car. Guide grips shall have 
not less than f-inch clearance. 

75. Guide grips must be operated by an endless standard iron 
hoisting rope passing through a clamping device, controlled by a 
centrifugal governor at top of hoistway and around a weighted 
idler at bottom of hoistway. A phosphor-bronze cable passing 
around a drum under car must be attached to the iron cable in 
such a manner that when rope is clamped drum is to revolve and 
operate the guide grips by means of screws. 

76. In lieu of above the bronze cable may pass around a block- 
and-fall device under car, which, when cable is clamped, will 
operate the guide grips. 

77. The guide grips shall be tested by dropping car with a 
net load on the platform equal to two-thirds the maximum load 
specified. 

78. The total distance traveled by the car after the rope has 
been cut shall not be less than 6 feet nor more than 9 feet. Car 
must not be out of level, when grips have set, more than \ inch 
in each foot of length between guide rails. Governor must be 
set for 140 per cent of contract speed. 

79. Provision must be made to release guide grips without 
going under the car. 

80. The test is to be made before connecting the cables. It 
is to be made at the building in the presence of the department's 
representative, who will advise the department when a satisfac- 
tory test has been made. 



274 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

81. Automatic limit switches. Switches operated from drum 
shaft must be provided to stop car at upper and lower landings 
independent of operator. The variation in point of stopping 
with no load and full load on car shall not exceed 12 inches. 

82. Ultimate limits. Limit switches are to be provided in 
hoistway which open potential switch when car travel is exceeded 
in either direction. These limits shall be located* at least 12 
inches beyond the maximum travel at which automatic limits 
stop car. 

82 a. All safeties except drum-shaft limits must perform their 
functions whether the main-line phases are in proper relation or 
not. 

83. All limit switches are to be butt contact of ample size. 
If limits break main-line circuits, current densities shall not ex- 
ceed twice that specified for controller contacts. 

Paragraphs 84 to 108 inclusive same as for direct current. 
Paragraphs 109, 110 and 111 substitute the following: 

109. Tablet. This contractor will be required to furnish and 
install near elevator machine a polished black slate tablet, treated 
to prevent absorption of moisture, not less than 1J inches thick, 
or, if mounted with controller board of same thickness, having 
mounted thereon one to 300 volt alternating-current voltmeter 
with switch for connecting same into any phase, and one alter- 
nating-current ammeter of proper range to indicate the maxi- 
mum starting current. Ammeter shall be connected through a 
double-pole, double-throw switch and two single-pole, single-throw 
switches, as indicated by diagram, to permit ammeter to be 
thrown out of circuit or into either of two phases. All spacing 
of switches, etc., on tablet to be for 250 volts. 

110. Instrument shall be of approved pattern, practically dead 
beat in action, inclosed in metal cases arranged for surface mount- 
ing on switchboard. 

111. All connections are to be made on back of board by cop- 
per bars and copper lugs for the reception of conductors. 

Paragraphs 112 ro 136 inclusive same as for direct current. 
Paragraphs 137 to 140 inclusive substitute the following: 
137. Motor. Motor to be wound for 220 volts, 3-phase, 60 
cycles alternating current. Motor to be of induction type with 
rotating secondary, of the squirrel-cage type, of ample power to 



ELEVATORS 275 

perform the work required and capable of withstanding overloads 
of 50 per cent. 

138. The insulation resistance between conductors and frame of 
motor must not; be less than 1 megohm, and the insulation must 
have a dielectric strength to withstand 1,500 volts alternating 
current for one minute. 

139. The motor must be capable of carrying full rated load as 
specified for a period of one-half hour continuous run, with a 
rise in temperature of windings and core not exceeding 50°C. 
above the temperature of the surrounding atmosphere. Tem- 
perature to be measured by thermometers shielded by cotton 
waste. 

140. Switch. Furnish and mount on tablet containing ele- 
vator switches and instruments one 60-ampere, 220-volt, triple- 
pole, single-throw knife switch with inclosed indicating fuses for 
controlling air compressor, Make necessary electrical connec- 
tions between elevator feeders, switch governor, and motor. 

Paragraphs 141 to 152 inclusive same as for direct current. 

INSTRUCTIONS RELATIVE TO THE INSPECTION AND TEST OF NEW 

ELEVATORS 

First ascertain if the elevator will lift the specified load at speci- 
fied speed. To ascertain speed points, mark off in hoistway about 
6 feet above the bottom landing and about 6 feet below top land- 
ing. Place paper at these points and measure distance between 
them. Then have car started from first floor, with speed load as 
specified, and with stop watch ascertain time required for car 
floor to pass the marks set as above noted. This will determine 
if specified speed-load duty has been fulfilled. 

Then place the maximum load on car and take speed as be- 
fore. The car should lift the maximum load at a speed within 
30 per cent of the speed specified in connection with speed-load. 

With the maximum load on car, take speed UP and DOWN 
and see if speed DOWN (with controller in full speed position) 
exceeds UP speed by more than 15 per cent. If so, the machine 
is not in compliance with office specifications. 

After tests above noted, see that motor temperature is not ex- 
cessive and that all parts of the machine work smoothly. 



276 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Make it a point to have the prospective elevator conductor 
present at the test and see that he is well instructed in the care, 
adjustment, and operation of the elevator. Place him in the car 
and make him cover a mile run with the stops at all landings in 
both directions. Ride in car, and observe if there is any objec- 
tionable side or end play in car, or any disagreeable grinding of 
the guides and counterweights. 

During the mile run, observe also the operation of elevator 
machine and see that motor and bearings are running smooth and 
cool. 

After all these tests have the guide-grip safeties tripped and see 
that they act promptly and stop car. Also see that a regular 
operator is instructed in the manner of tripping governor and re- 
setting safeties. 

It is customary to have one drop test of safeties made in the 
presence of the government's representative at the building. 
If this has not been done have the representative of the elevator 
company unshackle the cables and raise car up to about 15 feet 
above first floor and suspend same with a rope. Have safety 
device examined and when elevator man is ready have him cut 
the rope and let the car fall. 

The distance traveled by car after rope is cut must not be less 
than 6 feet nor more than 9 feet. 

In lieu of cutting cables the following test may be used under 
the following conditions: 

Speed tests are practicable only on direct current installations 
and are made by speeding up the motor through the medium of 
inserting resistance in series with the shunt field. A hand rheostat 
of a capacity to carry the current, and connected in series with the 
shunt field, is employed, starting up the machine with all the re- 
sistance in this rheostat cut out. The inspector should immedi- 
ately proceed to cut in resistance in the shunt field circuit with the 
ultimate purpose of increasing the motor speed not over 50 per 
cent at which speed, or at a slightly lower speed the governor 
should trip and operate the safeties. The inspector should check 
this increase in motor speed by tachometer held in place by an 
assistant, and the rate at which the motor is speeding up by cut- 
ting in the resistance should be determined somewhat by the rise 
of the elevator, and, of course, by the rate of increase in motor 
speed. 



ELEVATORS 277 

A speed test is possible only when wedge clamp safeties are 
used, when the elevator speed is normally over 100 feet per minute, 
and when the rise of the car exceeds 30 feet. 

After capacity test has been made, test the automatic terminal 
stop mechanism on the machine by running car at full speed into 
both limits of travel with controller handle held over to full speed 
position. Test the limit switches in hatchway by cutting out 
machine terminal apparatus. 

When safety governor is tripped, as before noted, see that the 
slack cable device has operated properly. 

Pay special attention to the terminal stop mechanism, as this 
and the cables are two of the most important safety features. 

Before making speed load tests, above noted, connect in circuit 
the ammeter and voltmeter, and during test for capacity take 
readings for accelerating and running current. In this test, even 
with dead-beat instruments, allow 5 per cent kick on first rush of 
current in computing the starting current in comparison with 
running current. The accelerating current is* not to exceed the 
running current by more than 35 per cent when direct current is 
used, and not over 200 per cent when alternating current is used. 
See whether the voltage fluctuates badly, and, if so, be careful to 
allow for it in calculations. 

See that the elevator accelerates in 5 seconds in making th^ 
above test. After test, adjust the controller so that the car will 
accelerate in 3 seconds if this quicker acceleration does not give a 
poor start. 

After capacity test reduce load gradually until the current re- 
quired to run car up is same as that required to come down, in- 
dicating a balanced condition of car, and note the balancing load 
in reporting on results. 

Instruct custodian to take up the matter of the supply of oil 
for operating the elevator with the office. 

Be sure that the man who will be in charge of the elevator is 
fully instructed as to oiling machinery; the proper oil to be placed 
in gear case; use of lubricant on cables; care of commutator and 
controller and care and oiling of guide rails. 

It must be borne in mind that technical ability of the man in 
charge of the elevator, and the care and skill of the elevator con- 
ductor, are the most important factors of safety in connection 
with the operation of the machine. 



CHAPTER IX 

SMALL POWER PLANTS 

WITH SPECIAL REFERENCE TO INSTALLATION IN FEDERAL BUILDINGS 
UNDER CONTROL OF THE TREASURY DEPARTMENT 

In determining whether the mechanical equipment of a Federal 
building should include a power plant for generation of elec- 
tric current for light and power, the following items require 
consideration : 

The cost of current if supplied by local electric companies. 

First cost. 

Whether suitable space is available. 

Difference in cost of salaries for power plant operation as com- 
pared with salaries in connection with operation of a low-pressure 
heating system. 

Increase in total cost of fuel required for the power plant above 
that required for a low-pressure heating system. 

Increase in cost of water used on account of exhaust steam 
wasted to the atmosphere. 

Interest charge on first cost. 

Depreciation charge (amortization). 

(Interest and depreciation are assumed as 8 per cent of the first 
cost of the plant.) 

In arriving at the cost of the plant the following figures are 
used: 

Single-valve direct-connected simple engines and genera- 
tors, per kilowatt, in place $35 .00 

Single-valve direct-connected compound engines and gen- 
erators, per kilowatt, in place 45.00 

Four-valve direct-connected simple engines and generators 
per kilowatt, in place. .* 45.00 

Four-valve direct-connected compound engines and gen- 
erators, per kilowatt, in place 55 .00 

Water-tube boilers and setting, with breeching and stack, 

per horse power, in place 30.00 

Switchboard and mountings, per panel, in place 300.00 

Piping, pumps, feed-water heater, etc., in place, at 20 per 
cent of the cost of the boilers, engines, and generators. . 

278 



SMALL POWER PLANTS 279 

The estimated cost of labor for operation is generally the most 
important factor in determining whether a plant shall be in- 
stalled. For operation of the average small plant in a Federal 
building the following force will usually be found sufficient: 

One chief engineer, at $1600 per annum. 

Three assistant engineers, at $1200 per annum. 

One engineer's helper, at $1000 per annum. 

Three firemen, at $2.50 per day. 

Two coal passers, at $2.00 per day. 

One fireman helper at $2.25 per day. 

In the same building with no electric generating plant and with 
electric elevators the following force will usually be found sufficient : 

One chief engineer, at $1400 per annum. 

Two assistant engineers, at $1000 per annum. 

Three firemen, at $2.25 per day, for seven months in the year. 

One fireman helper, at $2.00 per day for twelve months in the 
year. 

Two coal passers, at $2.00 per day for seven months in the 
year. 

To approximate the amount of coal required to heat the build- 
ing, ascertain the amount of radiation, both direct and indirect, 
reducing the latter to the equivalent of direct radiation by mul- 
tiplying it by 3 if a fan is used with the system, or by If if the cir- 
culation of air is by natural means. Assume that each square 
foot of direct radiation or its equivalent will condense 500 pounds 
of steam in a season of 200 days, and that when boilers are oper- 
ated for heating only there will be evaporated 7 pounds of water 
per pound of coal. If only the cubic contents of the building 
are known, a fair average for buildings in the latitude of New 
York City will be 1 square foot of radiation per 100 cubic feet of 
the contents. 

To approximate the additional amount of coal required to 
operate a generating plant, ascertain the size of the generating 
units as hereinafter described, and assume that the large unit 
will operate under a fluctuating load varying from § to 1* load 
16 hours a day for 165 days, and that the small unit will operate 
under the conditions noted above 8 hours a day. The steam 
consumption per indicated horse-power of the engines under the 
varying loads is taken from the tables hereinafter given, and the 



280 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

total steam consumption in pounds for the two units is reduced to 
pounds of coal on the assumption that 8 pounds of water will be 
evaporated per pound of good bituminous coal. 

General arrangement of the apparatus. In connection with 
electric generating plants in Federal buildings, all-steel water tube 
boilers are installed, if possible, and are designed for a safe work- 
ing pressure of 150 pounds per square inch, the usual operating 
pressure being 125 pounds per square inch. 

The size of the boiler plant is generally governed by the heating 
and ventilating requirements, as same are heavier in practically 
all parts of the country than are the requirements of power for 
operating the engines. A close approximation of the boiler re- 
quirements for direct heating is made by allowing one boiler 
horse-power for each 7000 cubic feet of contents of the building. 

In event the heating and ventilating requirements and space 
conditions are not the governing factors in determining the num- 
ber and size of the boilers, the day load and evening load on the 
generating plant are determined by the method hereinafter de- 
scribed; and the day load plus the evening load divided by 2 will 
give the size of the boiler units from which the best results will be 
obtained, one boiler being sufficient to carry the full load, with 
some margin, on the daylight run, and the evening load by slightly 
forcing the fires. This can easily be done by cleaning the fires 
toward the end of the daylight run and working up a strong deep 
fire for the commencement of the evening load. Three boilers 
of the size above noted would generally be installed. 

The minimum size of water-tuber boiler installed is 100 H.P. 

The clear heights which must be allowed from bottom of pit to 
underside of ceiling beams to insure a proper installation for the 
water-tube boilers used by the office are as follows: 

feet inches 

For boilers of 100 to 150 H.P 14 6 

For boilers of 150 to 175 H.P 15 

For boilers of 175 to 200 H.P 15 6 

These boilers are based on 10 square feet of water heating sur- 
faces per horse-power, and are always equipped with some kind 
of smoke-preventing apparatus. 

The boilers are arranged, when possible, to give a short, direct 



SMALL POWER PLANTS 281 

connection to the stack, and are so located as to be close to the 
engine room and convenient to the coal and ash rooms. 

A firing pit (especially a deep one) is always a detriment and is 
avoided if possible. 

The boiler and engine rooms are ventilated by drawing the hot 
air away from the ceiling by a fan or by fans, and allowing the 
cold air to flow in by gravity through doors and windows so 
arranged that firemen will not be subjected to a cold draft. 

The location of the engine room either directly in front or di- 
rectly at the rear of the boiler room gives the shortest pipe con- 
nections, and hence the least friction and condensation in the 
steam mains. 

This arrangement of engine and boiler rooms also allows for 
increase in the boiler, engine, and switchboard capacity by lateral 
extension, giving at all times a neat and compact arrangement of 
apparatus, and one which is economical both in first cost and in 
operation. 

Arranging the engines with cylinders on center lines parallel 
with center lines of boilers, and close to partition between boiler 
and engine room (5 to 10 feet clearance between wall and cylinder 
head) further shortens steam and exhaust connections. 

Size and number of generating units. The full connected 
lighting and power load is ascertained, special attention being 
given to accurate determination of the rated horse-power of all 
elevator motors, as this item has an important part in determining 
the size of the units. The starting current of elevators is never 
less than 35 per cent in excess of the maximum running current 
with direct-current motors, and rises to 200 per cent with alter- 
nating-current motors. 

Federal buildings in which generating plants are installed are 
all 24-hour buildings, and no breakdown connection is made 
with the local lighting companies; therefore the plants are made 
larger than in commercial practice, and never less than three units 
are installed; generally two large units, each sufficient to carry 
the peak load, and one small unit to carry the after-midnight 
load. 

Usually , with a view to insuring as far as practicable continuous 
operation, a four-unit plant is selected, comprising two large units, 
each able to carry the peak load, and two small units, each capable 
of carrying the after-midnight load. 



282 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



No unit smaller than 75 kilowatts, and generally none larger 
than 150 kilowatts is installed. The reason for not using a unit 
smaller than 75 kilowatts where an intermittent power load pre- 
vails needs no explanation, while space conditions, etc., gener- 
ally forbid the installation of units exceeding 150 kilowatts. 

To determine accurately the proper number and size of units 
within the limits stated, further analysis is made, as follows : 



Constant load, consisting of. 



Intermittent load, consisting of. 



fa percentage of the total number of 

| lights connected. 

{ a constant power load consisting of 
certain motors likely to be run con- 
tinuously. 

electric elevators, motors for mail 
lift, ventilating fans, house pump 
air compressors, circulating pumps 
(if used), vacuum cleaning machine, 
automatic temperature-control ap- 
paratus, air washer-motors. 



In determining the size of the units, the power demand should 
be analyzed under "day load" and "night load" conditions. 
With the post office operating all night the heaviest demand for 
current will be between the hours of 4 p.m. and 10 p.m., while 
from 11 p.m. to 6 a.m. the demand will be the smallest. 

The day load will consist of a small lighting load plus a con- 
stant power load plus an intermittent power load, all of which 
may be determined approximately, as follows: 



Lighting. 



Day load. . . . 



30 per cent of basement lights. 
J 20 per cent of post-office workroom lights. 
] 10 per cent of first-floor corridor lights. 
[ 5 per cent of office lights on all floors. 



{ventilating fan motors, 
circulating pump motor for air 
washer. 



Power. . 



Intermittent. 



electric elevators, 
house pump. 
< mail hoist motor, 
air compressor, 
vacuum cleaning motor, etc. 



SMALL POWER PLANTS 283 

The constant power load can be accurately determined, as it 
should not be difficult to decide definitely what ventilating fans, 
pump motors, etc., will be operated more or less continuously. 

After the day-load conditions have been thoroughly investi- 
gated the load conditions of the evening and after-midnight runs 
should be determined, as follows: 

[70 per cent of all post-office workroom lights. 
| 30 per cent of all basement lights. 

Evening load <! 60 per cent of first floor corridor lights. 

| small power load for fan, pump, or similar 
[ service, determined from the plans. 

[40 per cent of all post-office workroom lights. 
| 30 per cent of all basement lights. 

After-midnight load <{ 30 per cent of all first-floor corridor lights. 

small power load to be determined from the 
plans. 

• If the day load plus the after-midnight load is equal to or greater 
than the maximum or evening load, one unit should be selected 
with full-load rating equal to the day load, and one unit with 
full-load rating equal to the after-midnight load. These two 
units can then be operated in parallel to carry the maximum or 
evening load. 

The capacity of the spare unit is made equal to the day load. 

If, however, the maximum load is greater than the sum of the 
day and after-midnight loads, the size of the smaller unit must be 
equal to the difference between the day load and the maximum or 
evening load. 

As hereinafter stated, the large units must never be less in 
capacity than four times the rated kilowatt capacity of all ele- 
vator motors which may be in use at one time. 

When the day load is larger than 150 kilowatt, two or more 
units, preferably of equal capacity, are chosen. 

To illustrate the method of proportioning units: 

Assume that the constant light and power day load is 110 kilo- 
watts, and that two electric elevators are intermittently in use, 
each having a motor rated at 10 kilowatts, and each motor re- 
quiring 15 kilowatts to start. The maximum instantaneous load 
possible under the conditions is 110 plus 15 plus 15, or a total of 
140 kilowatts. 



284 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

A 125-kilowatt unit would be selected for this case, as said 
machine has an overload capacity of 156 kilowatts for two hours. 
The generator could easily take care of a vacuum-cleaner or 
other small motor in addition to the load stated. 

For another example; assume that the constant light and 
power day load is 50 kilowatts, and that there are two electric 
elevators in service, each having a motor rated at 10 kilowatts 
and requiring a starting current of 15 kilowatts for each motor, 
or a total of 30 kilowatts intermittent load. A 75-kilowatt gen- 
erator would be selected for this service. 

In selecting the size of a generating unit which must carry the 
constant power and light day load and also an elevator load, the 
size of the generator should never be less than four times the 
rated kilowatts of all the electric elevators which may be in use. 
The relation of the generator capacity to the intermittent elevator 
load must not be overlooked or the voltage regulation will be 
poor and the lights will blink when the elevators start. 

In commercial practice the generator capacity is, under adverse 
conditions, sometimes made only 2 \ times the rated kilowatt 
capacity of the elevator motors, but the results are bad. 

The foregoing methods of determining the generating unit 
capacity are for buildings where the larger unit will not exceed 
150 kilowatts. When conditions arise which require the design 
of a plant involving much larger capacities, and where perhaps 
from four to ten elevators are in daily use, it is advantageous 
to provide and operate two units in parallel for the day load in 
lieu of one; or one large one and three of one-half its capacity 
sometimes will prove a better arrangement, depending on the rela- 
tive proportion of the constant and intermittent loads, etc. 

No hard and fast lines can be laid down to govern the size of 
generating units, but the procedure is substantially as stated. 

TYPE OF ENGINES 

By reason of the advancement in steam engineering in recent 
years, a number of types of steam engines suitable for operating 
electric generators are available, each type possessing some merit 
peculiar to itself which adapts it to fill to best advantage certain 
operating conditions. 

The simple and compound high-speed single-valve, and simple 



SMALL POWER PLANTS 285 

and compound medium-speed Corliss-valve engines are the prin- 
cipal types offered. These engines are inclosed, self-oiling, and 
equipped with automatic shaft governor. They are built either 
horizontal or vertical and are arranged for direct connection to 
an electric generator. 

No arbitrary rules can be laid down to determine the choice 
of the proper type of engine, and each particular installation re- 
quires individual consideration. Floor space, size of unit,, cost 
of coal, characteristics of load, steam pressures, building heating 
requirements, and initial cost of installation are the principal 
factors which govern such selection. 

Simple single-valve engine. This type has the fewest me- 
chanical parts of any of the types mentioned, which commends 
it in all cases where a minimum of attention is desired and at- 
tendants of only average ability are employed. It is also the 
least expensive, which further commends it where first cost is a 
factor. On the ground of relatively smaller investment and 
depreciation, it is usually selected for small units ranging up to 
and including 50 kilowatts capacity, as in these sizes the saving 
of other types in steam does not offset the fixed charges. This 
type is also recommended in somewhat larger sizes where coal 
is not expensive (say $2 or less per ton), and for installations 
where the unit is in service for but short periods. It is also well 
adapted for use in buildings which must be heated during a large 
part of the year, or where the demand for steam heating exceeds 
in amount the engine exhaust. 

The speeds of this type of engine range as follows : 

Size kilowatt Revolutions per 

capacity minute 

25. ' 300-450 

35 300-350 

50 275-325 

75 250-325 

100 ' 250-300 

125 225-275 

150 200-260 

200 150-225 

250 150-220 

300 150-200 

The steam consumption per indicated horse-power per hour for 
all the different sizes given above should not exceed the following 



286 



MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 



amounts when operating with atmospheric exhaust and at the 
initial steam pressures stated: 



I. S. P. 


QUARTER 
LOAD 


HALF LOAD 


THREE- 
QUARTER 
LOAD 


FULL LOAD 


ONE 

AND ONE- 
QUARTER 
LOAD 


pounds 

80 


pounds 

48.9 
44.0 
40.5 
37.6 
35.3 
33.9 
32.5 
31.6 


pounds 

37.8 
35.4 
33.4 
31.7 
30.2 
29.0 
28.1 
27.1 


pounds 

34.3 
32.4 
30.9 
29.6 

28.5 
27.6 
26.2 
25.8 


pounds 

33.8 
32.0 
30.6 
29.2 
28.1 
27.2 
26.3 
25.6 


pounds 

34.3 


90 


32 5 


100 


31.1 


110 


29.7 


120 


28.4 


130 


27.7 


140 


26 9 


150 


26.1 







The mechanical efficiency of engines of this type is usually not 
less than 95 per cent for engines under 300 H.P. capacity and 94 
per cent for larger sizes. 

Simple Corliss- valve engine. This type is a development of the 
releasing Corliss-valve gear engine and partakes of its character- 
istics so far as steam consumption is concerned. By reason of 
fewer parts, without auxiliary cut-offs, dash-pots, etc., more ad- 
vantageous regulation and speeds are obtainable, making it ad- 
mirably suited for installation in Federal buildings, where the 
available floor space is usually limited. It is recommended for 
units 75 kilowatts in capacity and above, for localities where coal 
costs over $2 per ton, and with steam pressures in general use 
which range from 110 to 125 pounds. 

The steam consumption curve of engines of this type is very 
flat throughout its range, which adapts it for installations, with 
fluctuating loads. This, combined with the high mechanical 
efficiency, commends this type for the usual Federal building 
installation. 

The usual speeds of Corliss-valve engines are about as follows: 

Size kilowatt Revolutions per 

capacity minute 

75 225-250 

100 225-250 

125 200-225 

150 200-225 

200 150-200 

250 150-200 

300 150-200 



SMALL POWER PLANTS 



287 



Steam per indicated horse-power per hour required by engines 
of this type when operating at the initial steam pressures stated 
and with atmospheric exhaust should not exceed the following 
amounts for any of the sizes above noted : 



I. S. P. 


QUARTER 
LOAD 


HALT LOAD 


THREE- 
QUARTER 
LOAD 


FULL LOAD 


ONE 
AND ONE- 
QUARTER 
LOAD 


pounds 

80 


pounds 

40.0 
37.0 
34.8 
33.3 
32.4 
31.8 
31.2 
30.4 


pounds 

29.6 
27.8 
26.4 
25.3 
24.5 
24.0 
23.6 
23.1 


pounds 

27 .4 
26.1 
24.8 
23.8 
23.1 
22.6 
22.2 
21.8 


pounds 

27.5 
26.4 
25.3 
24.3 
23.6 
23.0 
22.6 
22.3 


pounds 

28.8 


90 


27.5 


100 


26.4 


110 


25.3 


120 

130 


24.7 
24.2 


140 


23.8 


150 


23.5 







The mechanical efficiency of simple Corliss-valve engines is 
usually not less than 94 per cent for engines under 300 H.P. and 
93 per cent for larger sizes. 

Compound single-valve engine. This engine is adapted for 
installations having comparatively high' steam pressures ranging 
upwards from 120 pounds with no back pressure, or operating 
condensing. As shown by the table of steam consumption fol- 
lowing, compound engines are not economical at light loads, and 
therefore constant approximate full loads are necessary for best 
results. 

The speeds of this type which are built either tandem or cross- 
compound, are about the same as given for the simple single-valve 
engines. 

The steam consumption per indicated horse-power per hour 
for engines ranging from 75 to 300 kilowatts should not exceed the 
amounts given in the following table when operating at the initial 
steam pressures given and with atmospheric exhaust. 

The amounts given in the following table are bettered approxi- 
mately 15 per cent for the quarter and half loads and 20 per cent 
for the other loads when operating condensing with about 24 
inches of vacuum; the amount of steam required for the con- 
denser, when condensing water is available, will average 7 per 
cent of the steam used by the engine, leaving a net gain of about 



288 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



I. S. P. 


QUARTEK 
LOAD 


HALF LOAD 


THREE- 
QUARTER 
LOAD 


PULL LOAD 


ONE 

AND ONE- 
QUARTER 
LOAD 


pounds 

100 


pounds 

48.6 
44.6 
42.4 
41.3 
40.3 
39.4 
38.7 
38.3 


pounds 

32.9 
29.5 
28.2 
27.6 
27.0 
26.5 
26.0 
25.6 


pounds 

28.2 
25.4 
24.3 
23.7 
23.2 
22.7 
22.2 
21.8 


pounds 

27.5 
24.6 
23.5 
23.0 
22.5 
22.0 
21.5 
21.1 


pounds 

28 


110 


25 


120 


24 


130 


23 4 


140 


22.9 


150 

160 


22.4 
21.9 


170 


21.6 







8 per cent for light loads and 13 per cent for heavier loads when 
operating condensing instead of with atmospheric exhaust. 

For engines of this type of less than 300 H.P. capacity, the 
mechanical efficiency is about 93 per cent, and in larger sizes about 
92 per cent. 

Compound Corliss-valve engine. This type of engine is recom- 
mended where proper operating conditions prevail and extreme 
economy is desired. These conditions are steam pressures of 120 
pounds or higher, comparatively steady full load, and exhausting 
with little or no back pressure, or operating condensing. 

The speeds at which engines of this type operate are about the 
same as given for simple Corliss-valve engines. 

The engines of this type ranging in size from 75 to 300 kilo- 
watts, when operating at the initial steam pressures given and with 
atmospheric exhaust, should not consume at varying loads more 
than the amounts per indicated horse-power per hour following: 



I. S.P. 


QUARTER 
LOAD 


HALF LOAD 


THREE- 
QUARTER 
LOAD 


FULL LOAD 


ONE 
AND ONE- 
QUARTER 
LOAD 


pounds 

100 


pounds 

47.0 
43.4 
41.2 
39.6 
39.0 
38.5 
38.0 
37.6 


pounds 

32.3 
30.0 
28.0 
26.8 
26.4 
26.0 
25.5 
25.0 


pounds 

26.7 
24.3 
22.5 
21.3 
20.9 
20.5 
20.1 
19.8 


pounds 
25.2 
22.6 
21.1 
19.8 
19.4 
19.0 
18.7 
18.4 


pounds 

24.9 


110 


22.7 


120 


21.3 


130 


20.3 


140 


19.9 


150 


19.5 


160 


19.1 


170 


18.8 







SMALL POWER PLANTS 



289 



The amounts given in the table above are improved about the 
same percentage when operating condensing as given under com- 
pound single-valve engines preceding. 

The mechanical efficiency of compound Corliss- valve engines of 
less than 300 H.P. capacity is usually not less than 92 per cent, 
and for larger sizes 91 per cent. 

Selecting an engine. To show the utility of the foregoing data, 
the following example is given for determining the proper engine 
to be selected under assumed conditions of operation: 

The engine is to be required to drive a 100-kilowatt generator 
with 110 pounds initial steam pressure, exhausting at atmospheric 
pressure; loads ranging between one-half and one and one-quarter 
full loads; units operating ten hours per day, 300 days per year, 
with coal costing $3.50 per ton. 

With a simple single-valve type the steam consumption for 
varjdng loads taken from the table is as follows : 



Steam consumption per I. H.P. 
per hour 



ONE-HALF 
LOAD 


THEEE- 

QUAETER 

LOAD 


FULL LOAD 


pounds 

31.7 


pounds 

29.6 


pounds 
29.2 



ONE 
AND ONE- 
QUARTER 
LOAD 

pounds 



29.7 



The steam required per hour at varying loads would be as 
follows : 



One-half load-31.7 lbs. 

Three-quarter load — 29.6 lbs. 

Full load-29.2 lbs. 

One and one-quarter load— 29.7 lbs. 



X 75 I.H.P. 
X 112.5 I.H.P. 
X 150 I.H.P. 
X 187.5 I.H.P. 



= 2,375 lbs. 
= 3,340 lbs. 
= 4,370 lbs. 
= 5,575 lbs. 

4)15,660 lbs. 



Average steam per hour 3,915 lbs. X 3,000 

hours = 11,745,000 lbs., the total steam required for the engine per year. 

With the simple Corliss-valve engine operating the same as 
above, with steam consumption taken from the table, steam re- 
quired per hour would be in accordance with the following : 






290 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



Steam consumption per I.H.P. 
per hour 



ONE-HALF 
LOAD 



pounds 



25.3 



THREE- 

QTJAKTER 

LOAD 



pounds 



23.8 



FULL LOAD 



pounds 



24.3 



ONE 
AND ONE- 
QUARTER 
LOAD 



pounds 



25.3 



One-half load-25.3 lbs. X 75 I.H.P. = 1,900 lbs. 

Three-quarter load-23.8 lbs. X 112.5 I.H.P. = 2,680 lbs. 

Full load-24.3 lbs. X 150 I.H.P. = 3,650 lbs. 

One and one-quarter load-25.3 lbs. X 187.5 I.H.P. = 4,810 lbs. 

4 )18,040 lbs. 

Average steam per hour 3,260 lbs. X 3,000 

hours per year = 9,780,000 lbs, yearly steam consumption. 

A compound single-valve engine operating under the same 
conditions will for varying loads require the following amounts of 
steam : 



Steam consumption per I.H.P. 
per hour 



ONE-HALF 
LOAD 



pounds 



29.5 



THREE- 
QUARTER 
LOAD 



pounds 



25 A 



FULL LOAD 



pounds 



24.6 



ONE 
AND ONE- 
QUARTER 
LOAD 



pounds 



25.0 



One-half load-29.5 lbs. X 75 I.H.P. = 2,210 lbs. 

Three-quarter load-25.4 lbs. X 112.5 I.H.P. = 2,860 lbs. 

Full load-24.6 lbs. X 150 I.H.P. = 3,680 lbs. 

One and one-quarter load-25.0 lbs. X 187.5 I.H.P. = 4,730 lbs. 

4)13,480 lbs. 

Average steam per hour 3,370 lbs. X 3,000 

hours = 10,110,000 lbs. steam per year. 

With a compound Corliss-valve engine the steam required at 
varying loads will be as follows: 



Steam consumption per I.H.P. 
per hour 



ONE-HALF 
LOAD 



pounds 



30.0 



THREE- 
QUARTER 
LOAD 



pounds 



24.3 



FULL LOAD 



pounds 



22. 6 



ONE 
AND ONE- 
QUARTER 
LOAD 



pounds 



22.7 



SMALL POWEE PLANTS 291 

One-half load -30.0 lbs. X 75 I.H.P. = 2,250 lbs. 

Three-quarter load-24.3 lbs. X 112.5 I.H.P. = 2,740 lbs. 

Full load-22.6 1bs. X 150 I.H.P. = 3,380 lbs. 

One and one-quarter load-22.7 lbs. X 187.5 I.H.P. = 4,290 lbs. 

4 )12,660 lbs . 

Average steam per hour 3,165 lbs. X 3,000 

hours = 9,495,000 lbs. yearly steam consumption. 

Comparing the performance of the simple single-valve engine 
with the simple Corliss-valve engine, there will be the difference 
between 11,745,000 pounds steam and 9,780,000 pounds, or 
1,965,000 pounds steam less required for the simple Corliss-valve 
than for the simple single-valve engine. Reducing this saving 
in steam to coal at 8 pounds evaporation, there is a total saving 
of 245,625 pounds of coal, or about 109 tons of 2240 pounds each. 
This saving in coal at $3.50 a ton amounts to approximately 
$381.00 per annum, which would justify the difference in the 
amount of investment in the two engines, roughly about $1200 

While the compound single-valve engine shows a gain over the 
simple single-valve engine, it is obviously insufficient to weigh 
against the selection of the simple Corliss-valve type; and as the 
compound Corliss-valve engine, in comparison with the simple 
Corliss-valve type, does not show enough gain to warrant selec- 
tion at its greatly increased price, it may be concluded that the 
simple Corliss-valve engine would be the proper one to choose 
under the assumed conditions. 

If the coal in the above example had been purchased for $1.50 
per ton, the yearly saving with the 'simple Corliss-valve engine 
over the simple single-valve engine would have been only $163.00, 
an amount insufficient to justify the expenditure of the additional 
sum necessary to purchase the simple Corliss-valve engine. 

The engine efficiencies have been ignored in the above calcula- 
tions, as the only object was to show the use of the tables and the 
method of calculating the steam required per indicated horse- 
power with different type machines. 

ELECTRIC GENERATORS 

The usual load consists of elevators, lighting, ventilating fans, 
and pumps, the elevator load being the major part of the total 



292 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

load. It is therefore desirable to use a generator of such char- 
acteristics that a fairly constant lighting voltage will be main- 
tained when the elevators are thrown on the circuit, and frequent 
overloads will be carried without sparking. 

These characteristics are best obtained in the interpole design. 

In a non-interpole generator, sparking is due primarily to a 
local magnetic field surrounding a coil which is being commutated. 
This field sets up a counter-electromotive force, or voltage, in the 
commutated coil in such a way as to oppose the reversal of the 
current in the coil, and thus tends to cause spark as the coil 
or commutator bar leaves the brush. This action increases with 
current or load, and is especially destructive at heavy overloads. 

In a non-interpole machine, sparkless commutation may be ob- 
tained if the brushes can be so located that the armature coils, 
short circuited by them, are brought into a magnetic field of 
exactly the right direction and strength to neutralize the effect 
of the local field at the moment of commutation. 

Such a field is found to exist near the tips of the pole pieces, 
and it has been customary to advance the generator brushes 
sufficiently to bring the armature coils within its during commuta- 
tion; but this field varies in strength under various conditions of 
loads, and instead of becoming stronger as desired with increase 
of loads, it actually becomes weaker. 

Interpole generators. In interpole generators the proper con- 
ditions for commutation are obtained by the use of small poles 
interspaced between the main poles. 

The interpoles have their windings in series with the armature 
and set up magnetic fields which annul the effect of the fields 
formed by armature magnetization, and generate in the commu- 
tated coils an electromotive force which assists the reversal of the 
current. Since the interpole coils are in series with the armature, 
the interpole field strength varies in proportion to the load, and 
it thus has the proper corrective effect at all loads. 

Since the electromotive force due to the interpole which assists 
reversal has a definite position under the interpole, the coil being 
reversed must also be located accurately with respect to this re- 
versing electromotive force. The brushes are consequently lo- 
cated on the true neutral point, and experience proves that spark- 



SMALL POWEE PLANTS 293 

less commutation can be obtained under practically all conditions 
from no-load to very heavy overloads. 

Commercial kilowatt and speed ratings of direct-current 
generators. Standard commercial speeds and kilowatt capacities 
from 25 kilowatts to 300 kilowatts for 125-volt, 250-volt, and 
125-250-volt 3-wire generators are as follows for interpole 
machinery : 

Kilowatt R.P.M. 

25 295-305-310-325 

35 285-305-315 

50 275-280-290-300 

75 250-265-275-290 

100 250-260-275 

125 225-250-260-275 

150 200-220-250-260-275 

200 100-150-200-210-220 

250 150-200-220 

300 100-120-150-200-220 

Late designs are provided with steel frames to produce rugged 
and stiff construction and at the same time to reduce the handling 
and shipping weights and permit light foundations. 

Ventilation. The later types of machines have open-end wind- 
ings on the armatures as well as air ducts in the armature cores. 
The shunt field coils are form-wound in comparatively long coils 
of small radial depth. The series and interpole coils are wound 
from bare copper strap insulated with spacers, with ample air 
ducts between the poles, shunt coils, and series coils, so that the 
armature and field windings of the generator are open to free 
ventilation. 

Temperature rise and overloads. Based on a room temperature 
of 25° C, the temperature rise at full load should not exceed 35° C. 
after continuous operation, nor 50° C. after two hours' operation at 
25 per cent overload. A small margin should be allowed, say 5° C, 
on the commutators of 125-volt generators. 

SPECIFICATIONS 

The following is a specification for engines and generators as 
prepared in the office of the Supervising Architect: 



294 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

ENGINES 

Type. The engines are to be of the single-cylinder, automatic, 
horizontal, side-crank type with gravity feed lubrication, and are 
to be designed to operate non-condensing on dry saturated steam 
at 110 pounds gauge pressure at the throttle; the speed of the 100- 
kilowatt generator engine to be between 225 and 250 revolutions 
per minute, and that of the 50-kilowatt generator engine to be 
between 275 and 300 revolutions per minute. 

Capacities. The engines are to be designed so as to operate 
most economically when generators are delivering three-quarter 
load at the rated voltage and speed, and shall be capable of oper- 
ating the generators for two hours when delivering 25 per cent 
overload ab rated voltage. 

Foundations. Foundations to be of the required form to suit 
engine and generator sub-bases, and to be constructed of 1:2:3 
concrete with the bottom not less than 4 feet below the floor line. 
The top must extend not less than 6 inches beyond the edge of 
sub-base frames all around, and the batter in the depth specified 
must be not less than 3J feet each side. Concrete foundations to 
be provided with cushion of 6-inch deep sand. Foundation bolts 
to be provided with washers and wrought-iron sleeves. 

Sub-bases. Each engine to be provided with a heavy and sub- 
stantial cast-iron sub-base upon which shall be mounted the 
engine; the sub-base of the 100-kilowatt generator engine to be 
extended under cylinder for support of cylinder. 

The sub-base of generators must be secured to engine sub-base 
with suitable bolts and dowels, and both sub-bases secured to the 
foundations. 

Frames. Each engine to be provided with a heavy and substan- 
tial cast-iron frame designed for strength, rigidity, and compact- 
ness, and to be provided with suitable covers to prevent throwing 
oil and allowing dust to come in contact with the moving parts. 

Bearings. Each engine to have two bearings; one to be set in 
the engine frame and the other to be outboard beyond the genera- 
tor. Bearings shall be long, well-proportioned, and dust proof. 
The out-board bearing to be of the oil ring type. Bearings to be 
lined with genuine babbitt metal carefully peened in place and 
accurately bored to gauge. The bearings to be provided with - 



SMALL POWER PLANTS 295 

large size oil wells, visual gauges, and petcocks for drawing the 
oil. Bearings to be provided with means for adjustment. 

Lubricating system. Each engine to be provided with an 
automatic self -lubricating system which shall supply pure, clean 
oil continuously to all bearings, etc., the operation of system to be 
positive and free from throwing or spilling the oil, and arranged 
to reuse the oil. 

Cylinders. Each cylinder to be made of best grade of close- 
grained cast iron, bored true and smooth, and of sufficient thick- 
ness to allow for reboring. The cylinder to be well lagged with 
magnesia or other material having equal heat insulating value, 
and covered with ornamental cast-iron jackets or with Russia 
iron, properly secured to the cylinder casting. 

Pistons. The piston heads shall be hollow cast iron, with at 
least two snap rings with lap joints, made from first quality of 
hard, close grain cast-iron sprung into accurately fitting grooves. 
Rings shall override the bore of cylinder. Piston rods to be best 
quality nickel steel. Rods to be turned to a taper at the piston 
ends and each driven up to a shoulder and securely held by a 
heavy nut to be drilled and provided with cotter pin. The for- 
ward ends to be screwed into crossheads and provided with jam 
nut to prevent turning. 

Crossheads. The crossheads to be made of cast iron or steel 
and be provided with adjustable bronze shoes circular in form. 
Crosshead pin to be made of steel hardened and ground and held 
in place by taper fit and nut. 

Connecting rods. The connecting rods to be forged open- 
hearth steel in one piece with solid end and crosshead ead. The 
crosshead boxes to be made of phosphor-bronze adjustable by 
means of wedge. Crank ends to be fitted with boxes of steel lined 
with genuine babbitt metal peened and bored to fit the pius. 

Crank shafts. Crank shafts to be constructed of open-hearth 
steel forged in one piece, with count erbalanciug crank disks of 
annealed steel, securely fastened thereon. 

Valves. The valve for the 50-kilowatt generator engine to be 
perfectly balanced, of the adjustable type, constructed of best 
quality hard close-grain cast iron, operated in removable bushings 
or pressure plates. 

The 100-kilowatt generator engine to be fitted with four valves 



296 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

of the semirotary or gridiron type, designed to be slightly un- 
balanced and securing positive steam-tight seating over the ad- 
mission ports. Steam valves to be of the multiported type giving 
ample port openings for all points of cut-off. Exhaust valves 
to be designed to give ample port area and insure tightness. All 
valves to be constructed of best quality hard close-grain cast 
iron. Semirotary steam valves to be provided with removable 
bushings or cages; gridiron valves to be provided with suitable 
balancing plate. 

Valve mechanism. The valve mechanism on each engine to be 
designed to give quick and positive motion to the valves in open- 
ing and closing. All pins subject to wear to be made of steel 
hardened arid ground. All boxes for pins to be made of phosphor- 
bronze and be adjustable without filing. Lubrication of pins and 
bearings to be accomplished while in motion by compression 
grease cups placed at accessible points or to operate in oil wells. 

Eccentrics. The eccentrics to be strong and light to reduce the 
strain upon the governor springs, and hung on hardened steel pins 
operating in removable bronze bushings. The eccentric straps 
to be lined with best quality of antifriction metal. Ample means 
of lubrication to be provided and designed to be free from oil 
throwing when in motion. 

Governors. Each engine to be equipped with a centrally bal- 
anced centrifugal inertia governor which will maintain a perfect 
condition of balance in all positions of cut-off, and operate with 
equal ease and isochronism from zero to 62.5 per cent cut-off. 

The governor pins and bushings to be made of steel and bronze, 
the former hardened and ground true. The lever-arm bearing to 
be of the antifriction type. 

Steam consumption. Each bidder must state in proposal sheet 
the indicated horse-power, full load of each engine, and the maxi- 
mum steam consumption when operating under conditions herein 
specified at uniform varying loads, which will receive consideration 
in award of contract. 

Each engine when operated under conditions herein specified and 
at uniform varying loads must not consume more than the amount 
of dry steam in pounds per indicated horse-power per hour, deter- 
mined by the weight of condensed exhaust steam, for each load as 
stated below: 



SMALL POWER PLANTS 



297 



50-kilowatt generator engine, dry steam 
100-kilowatt generator engine, dry steam 



25 
per cent 



37.6 
33.3 



50 
percent 



31.7 
25.3 



75 
percent 



29.6 
23.8 



100 
percent 



29.2 
24.3 



125 
percent 



29.7 
25.3 



Shop test of engines. The efficiency, capacity, etc., of each 
engine to be determined by actual test in the presence of the 
Department's authorized agent, who shall determine the test 
conditions. 

The tests are to be made at the shop where engines are con- 
structed, and are to begin within ten days after receipt of notice 
from the contractors of their readiness to commence tests, and to be 
at the expense of the contractors, except traveling and other ex- 
penses of the Department's agent. 

Engines to be run at one-half, three-quarters, full, and one and 
one-quarter loads for one hour under each load, during which 
time the exhaust steam will be condensed and weighed, and 
indicator cards taken every five minutes. 

Engines to be run at the speeds specified with steam at 110 
pounds pressure per square inch at the throttle, quality of which 
will be determined by throttling calorimeter placed in steam pipe 
above throttle. 

Under above conditions the friction load must not exceed 5 
per cent of the normal capacity of engine for the 50-kilowatt gen- 
erator engine, and must not exceed 7 per cent for the 100-kilo- 
watt generator engine. 

It must be distinctly understood as one of the conditions under 
which bids are submitted for the work embraced in this specifica- 
tion that the engines must meet every requirement of the tests 
above specified, under which conditions the contract price will be 
paid. In the event the engines fail to meet the requirements for 
steam consumption or friction load, or both, the Department 
shall have the right to reject the engines absolutely and require 
the supply of satisfactory engines which comply with the specifi- 
cation requirements in regard thereto; or, if the Department 
elects to accept the engines, the contract price shall be the amount 
named in the contract for a satisfactory plant, less the amount of 



298 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

deficiencies shown by tests above described upon the following 
basis : 

Nine hundred dollars per pound or proportional part of said 
$900 for each fraction of a pound below the guaranteed efficiency 
for the 50-kilowatt generator engine, and $1800 per pound or 
proportional part of said $1800 for each fraction of a pound be- 
low the guaranteed efficiency for the 100-kilowatt generator engine, 
based on any or all of the varying loads, irrespective of economy 
at other loads. 

Two hundred and fifty dollars for each per cent or propor- 
tional part of said $250 for each fraction of a per cent above the 
specified friction load for the 50-kilowatt generator engine, and 
$500 for each per cent or proportional part of said $500 for each 
fraction of a per cent above the specified friction load for the 
100-kilowatt generator engine. 

The Supervising Architect reserves the right to waive these 
tests or any portion thereof and to require contractor to submit 
certified test sheets, in triplicate, for approval, it being under- 
stood that those portions not waived shall be exacted when ap- 
paratus is installed if not performed at shop as specified above. 

Regulation. After engines are installed in position they must 
be adjusted to run smoothly and practically noiselessly. They 
must be tested at shops for regulation, which tests must show 
that slow change from no load to full load and vice versa will not 
produce more than 1| per cent speed variation, and from full load 
suddenly thrown on or off the speed variation shall not be over 2 
per cent. 

Fittings. Each engine to be furnished with the following 
fittings : 

One throttle valve. 

Automatic cylinder relief and drain valves. 

Mechanical cylinder lubricator, piping, etc. 

Auxiliary hand oil pump. 

Steam chest drain connections with valves. 

Indicator piping with three-way cocks and angle globe valves. 

Attached indicator reducing motion. 

Set of adjusting wrenches on hardwood board. 

All necessary drip, drain, and indicator piping, which must be 
brass, nickel plated, exposed above floor. 



SMALL POWER PLANTS 299 

GENERATORS 

Type. Generators are to be direct-connected, engine-driven, 
interpole type for 125-volt direct current, each mounted on sub- 
base, connected to its engine sub-base. One to have full-load 
rating of 50 kilowatts and one to have full-load rating of 100 kilo- 
watts at the speeds determined by the full load speeds of engines 
which must be between the limits previously stated. Considera- 
tions will be given to proposals based on generators without 
interpole feature. 

The armatures and commutators to be built upon ventilated 
sleeves or spiders, arranged to be pressed on and keyed to shafts. 

The field or magnet frames to be provided with screws and liners 
for adjustment in position. 

Frames. The frames of generators to be made of a high-grade 
cast steel or of cast iron of high permeability, sound and free from 
blowholes. The seats for the pole pieces to be accurately finished; 
seats for the bolt heads and nuts to be faced. 

Poles. The poles to be made of laminated steel or iron, bolted 
to the frames. The interpoles to be of steel, bolted to the frames. 

Field Coils. The main field coils to be form wound, provided 
with ventilating ducts, and be so secured that they may be readily 
removed without unwinding; to be so proportioned as to auto- 
matically give the voltages specified under " Regulation;' 7 and be 
properly insulated in a substantial manner with material of the 
best quality and thoroughly tested. 

Armatures. The armatures to have slotted cores. The wind- 
ings to be thoroughly insulated, provided with ventilating ducts 
for cooling the windings, and coils to be securely held in place. 
The armatures must be balanced both mechanically and elec- 
trically. 

Commutators. Commutator segments to be of drop-forged or 
hard-drawn copper of highest conductivity, insulated with mica of 
even thickness and proper hardness to insure uniform wear, and 
must run free from sparking or flashing at the brushes at any load 
or during change of load. They must have ample bearing surface 
and radial depth for wear. 

Brushes. Brushes to be of carbon, of such size and number as 
will carry all the loads covered by this specification without in- 
jurious heating. 



300 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

With the fixed position of the brushes, there is to be practi- 
cally no sparking or burning of the brushes or blackening of the 
commutator within the limits of the time loads specified, nor any 
injurious sparking at the momentary overloads specified. 

Brush holders. The brush holders to be so constructed that 
the tension on any brush may be adjusted without lifting the 
brush from the commutator and without the use of any tools; 
and that any brush can be removed while the machine is in 
operation without disturbing the others and without moving the 
holder on the stud. Flexible connections to the brushes to be 
used to prevent injurious current in parts of brush-holder 
mechanism. 

The brush holders to be mounted on studs extending from suit- 
able yokes or rings, which must be supported from the frames. 

Regulation. The voltage regulation to be 110 volts no load to 
117 volts full load based on a variation of speed in the engine of 
not more than 2 per cent from no load to full load. 

Insulation. The frames of machine must have an insulation 
resistance from the field coils, armature windings, and brushes of 
not less than 1 megohm. Generators to be capable of standing 
a breakdown test of 1500 volts alternating current for one minute. 

Heating effect. Generators are to be run continuously at full 
rated load until all parts have reached a constant temperature and 
for one hour thereafter, at which time the temperature rise of 
the armatures and field coils shall not exceed 35° C. and of the 
commutator 40° C. above the surrounding air, corrected to 25° C. 

Immediately following the full-load run, and starting with tem- 
peratures not less than the final temperatures of full-load run, 
each machine shall be operated for two hours at 25 per cent over- 
load, at the expiration of which time the temperature rise of the 
armature and field coils shall not exceed 50° C. and of the com- 
mutator 55° C. above the surrounding air, corrected to 25° C. 

Efficiencies. The efficiencies of generators must not be less 
than the following: 



LOAD 


100-KILOWATTS 


50- 


-KILOWATTS 


One-half 


88.5 
89.0 
88.5 
87.5 




88.0 


Three-quarters '. 


88.0 


Full 


87.5 


One and one-quarter 


86.0 



SMALL POWER PLANTS 301 

Shop test of generators. The efficiency, heating effect, insu- 
lation resistance, etc., of generators shall be determined by actual 
test in the presence of the Department's authorized agent, who 
shall determine the test conditions. 

The test to be made at the shop where generators are con- 
structed, and to begin within ten days after receipt of notice 
from contractors of their readiness to commence test, and to be at 
the expense of contractors, except traveling and other necessary 
expenses of the Department's agent. 

The Supervising Architect reserves the right to waive these 
tests or any portion thereof and to require contractors to submit 
certified test sheets in triplicate for approval, it being under- 
stood that those portions not waived shall be exacted when ap- 
paratus is installed, if not performed at the shop as indicated 
above. 

THREE-WIRE GENERATORS 

In all new plants, and in all old plants in which the motor 
equipment and the generator sets are to be entirely replaced and 
the building rewired, the practice of the office now is to install a 
3-wire system and use 3-wire generators. 

The 3-wire system allows a saving of 25 per cent of the weight 
of copper in the feeders, when figures are on the basis of current 
capacity, and a saving of 62J per cent when figured on a basis 
of drop in potential; the neutral wire being considered as equal 
in size to one of the outside wires. The 3-wire system admits 
of using 110 volts for the lighting system, which is the most de- 
sirable voltage, and 220 volts for motors, which is the most de- 
sirable from a standpoint of first cost and general operating con- 
ditions. The half voltage obtainable from either side of the 
system is also desirable for variable-speed motor work or low 
voltage lamps. 

A 3-wire machine consists of a standard 2-wire machine with 
the additions described below. 

Four slip rings are mounted on the shaft and connected with the 
armature winding at intervals corresponding to 90 electrical de- 
grees, where 360 electrical degrees is taken as the distance between 
two poles of the same polarity. The voltage at the slip rings is 
2-phase alternating. 



302 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



The balance coils are connected one to each phase. 

Each balance coil has a neutral wire connected to its winding 
midway between the end. These are connected together and 
form the neutral of the 3-wire direct current system. One bal- 
ance coil could be employed but the 2-phase connection has been 
found to give a better distribution of current in the generator 
armature and a better voltage regulation. 

Balanced voltage. The action of the coils in balancing the 
voltage on the two sides of the system may be readily understood 
by reference to the accompanying figure. 

Only one coil is shown. It is connected through slip rings to 
points C and D of the generator armature. Windings and con- 
nections being symmetrical, it is evident that when the terminals 
of the balance coil C and D are directly under the brushes, that 




is, when the point D coincides with the point A and the point C 
with the point B, the balance coil is subjected to the full voltage 
of the generator and the potential between the middle point E 
and each outside wire is equal to one-half the generator voltage. 
Also, when the armature has rotated 90° further so that the point 
C and D lie directly under the poles, the balance coil is not sub- 
jected to a difference of potential and the voltages between the 
neutral and the outside wires on the two sides of the system are 
respectively equal to the voltages between D and A, and C and B. 
In any other position of the armature, the voltage between E and 
A is the resultant of half the voltage of the balance coil a ad the 
voltage of the segment of the armature winding between D and A . 
As the voltages generated in equal parts of the armature are 
equal, the voltage generated in segment AD equals that gener- 
ated in segment BC, and, since E is the midpoint of the balance 



SMALL POWER PLANTS 303 

coil so that the voltage between E and D is always equal to that 
between E and C, it follows that the voltage between E and A 
must always equal that between E and B, and that E is therefore 
the neutral point at all times. 

Armature. The armature winding of the standard Westing- 
house 2-wire generator is unchanged except the coils which have 
the taps brought out and connected to the collector rings. 

Fields. The series coils of compound wound 3-wire generators 
are divided into halves, one of which is connected with the posi- 
tive and one with the negative side. This is done to obtain 
compounding on either side of the system when operating on an 
unbalanced load. To show this more clearly consider the case 
of a generator with the equalizer in the negative side only and 
with the majority of the load on the positive side of the system. 
The current flows from a positive brush through the load and back 
along the neutral wire without passing through the series field. 
The generator is then operating as an ordinary shunt machine. 
If the majority of the load be connected to the negative side, the 
current flows out the neutral wire and back through the series 
field, boosting the voltage the same amount as a 250- volt load 
taking the same amount of current. Such operation is not satis- 
factory and so the two series fields are provided. 

Equalizers. As there are two series fields, two equalizer busses 
are required. 

Terminal boards. Owing to the equalizer connections, two 
similar terminal boards are supplied, one for each side of the 
generator. 

Ammeters. Two ammeters must be provided for reading the 
current in the two outside wires. It is important that the cur- 
rent be measured on both sides of the system, for, with ammeter 
in one side of the system only, it is possible for a large unmeasured 
current to flow in the other side of the system. 

Switchboard connections. One voltmeter is connected across 
the outside wires. Two ammeters should be used to indicate the 
unbalanced load. The positive lead and equalizer are controlled 
by a double pole circuit breaker, the negative lead and equalizer 
should be likewise protected. Both the positive and negative 
main leads and equalizers are ordinarily provided with single pole 
single throw switches. 



304 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

Unbalanced load. Standard balance coils are supplied of ca- 
pacity suitable for an unbalanced load of 10 per cent of the full 
load current, that is, a current in the neutral equal to 10 per cent 
of the full load current of the machine. For example, take a 100- 
kilowatt 250-volt generator. Full load current amounts to 400 
amperes, at 250 volts, 10 per cent of this amounts to 40 amperes. 

Regulation. The regulation of a 3-wire generator when oper- 
ating on a balanced load will be the same as any standard 2-wire 
generator. With 10 per cent unbalance, the variation in voltage 
between the neutral and outside wires will not exceed 2 per cent 
below or above normal. 

Balance coils. Each of these consists of a laminated core and 
single winding with a neutral tap brought out from its middle 
point. Whatever the A.C. voltage impressed on the ends of the 
winding, the voltage between one end of the winding and the 
neutral is one-half of the total voltage. Winding and core are 
enclosed in a cast-iron case, which is filled with transformer oil. 

In the event it is desired to use a 3-wire generator the foregoing 
specifications for a 2-wire generator are modified as follows: 

Type. The generators are to be direct connected, engine 
driven, interpole type for 3-wire 125-250 volt direct current, 
each mounted on a sub-base connected to its engine sub-base. 
One to have a full load rating of 50 kilowatts at 285 r.p.m. and 
one to have full load rating of 100 kilowatts at 250 r.p.m. 

The armatures and commutators to be built upon ventilated 
sleeves or spiders, arranged to be pressed on and keyed to shafts. 

The field or magnet frames to be provided with screws and liners 
for adjustment in position. 

Frames. The frames of generators to be made of a high grade 
cast steel or of cast iron of high permeability, sound and free from 
blowholes. The seats for the pole pieces to be accurately fin- 
ished, seats for the bolt heads and nuts fco be faced. 

Pole. The pole to be made of laminated sheet steel, bolted to 
the frames. The interpole to be steel bolted to the frames. 

Field coils. The main field coils to be form wound, provided 
with ventilating ducts, and be so secured that they may be readily 
removed without unwinding. The series field will be divided so 
that one-half will be connected in the positive line, one-half will 
be connected in the negative line; and so proportioned to auto- 



SMALL POWER PLANTS 305 

matically give the voltages specified under "Regulation," and be 
properly insulated in a substantial manner with material of the 
best quality. 

Armatures. The armature to have slotted cores, the windings 
to be thoroughly insulated, provided with ventilated ducts for 
cooling the windings and coils to be securely held in place. Pref- 
erence will be given to 2-phase, 3-wire connections on account 
of the better balanced voltage. The armature must be balanced 
both mechanically and electrically. 

Commutators. Commutator segments to be of drop forged or 
hard drawn copper of high conductivity, insulated with mica of 
even thickness and proper hardness to insure uniform wear; and 
must run free from sparking, flashing or burning at the brushes 
at any load or during change of load. They must have ample 
bearing surface and radial depth for wear. 

Brushes. Brushes to be of carbon, and of such size and num- 
ber as will carry all of the loads covered by this specification 
without injurious heating. 

With a fixed position of the brushes, there is to be practically 
no sparking, flashing or burning of the brushes, or blackening of 
the commutator within the limits of the time load specified or 
any injurious sparking at the momentary load specified. 

Brush holders. (No change.) 

Regulation. The voltage regulation to be 230 volts no-load to 
250 volts full load based on a variation of speed in the engine of 
not more than 2 per cent from no-load to full-load. 

With 10 per cent unbalanced load in the neutral wire or 40 
amperes for the 100-kilowatt generators and 20 amperes for the 
50-kilowatt generator the variation in voltage between the neutral 
and the outside wires will not exceed 2 per cent above or below 
normal. 

Insulation. (No change.) 

Heating effect. (No change.) 

Efficiencies. (No change.) 

Switchboard. (Must be changed to suit 3-wire system of 
distribution.) 



CHAPTER X 

MOTORS AND CONTROLLING APPARATUS 

DIRECT CURRENT 

The reasons given for using interpole generators apply more 
forcibly to direct-current motors. The instantaneous overload is 
large and more frequent, and the continued overload obtains 
more often on individual motors than on generators supplying 
several motors. Also the interpole provides the proper com- 
mutating field when motors are run at increased speeds by field 
control, and consequently with weaker magnetic conditions. 

The mechanical construction should be rigid but the weights 
should be kept down to the safe minimum. Steel frames are there- 
fore desirable from both standpoints. 

The bearings should be dust and oil proof. 

The efficiency should be high and the overload capacity ample. 

The speed should be approximately the same as the full load 
speeds of induction motors, thus simplifying the application of 
motors to pumps and fans, as it is desirable in some of the Federal 
buildings to use alternating-current circuits. 

It is desirable to operate motors on 220 (or preferably 230) 
volts, rather than at 115 volts. Standard commercial speeds and 
horsepower ratings from lj H.P. to 20 H.P. and 230 volts are as 
follows for interpole motors: 

Horsepower Full load R.P.M. 

U 900 

2 850-1200 

3 1150-1800 

5 850-1100-1800 

7\ 650-850-975-1150-1700 

10 600-730-850-1150-1300-1700 

15 600-675-825-1100-1250-1700 

20 650-750-900-1100-1700 

This table, however, applies to 115 volt interpole motors except 
7 J to 20 H.P. motors, inclusive, which are not usually built for 
1700 R.P.M. 

306 



MOTORS AND CONTROLLING APPARATUS 



307 



The commercial efficiencies of 230-volt interpole motors at full 
load are as follows: 



HORSEPOWER 




RATED SPEED 


3 






600 


720 


900 


1200 


1800 


1.5 


84.5 
85.0 
86.0 

87.5 


84.5 
85.5 
85.5 
88.0 


74.5 
76.5 
79.0 
83.5 

85.5 
87.0 
88.0 
88.0 


77.5 
80.0 
83.5 
85.5 
86.5 
88.5 
89.0 




2 




3 

5 


79.5 
81.5 


7.5 


86.0 


10 

15 

20 


86.0 

87.5 
88.5 



The commercial efficiencies of 115-volt interpole motors at full 
load are as follows: 



HORSEPOWER 


RATED SPEEDS 




600 


720 


900 


1200 


1800 


1.5 


84.5 

85.5 
87.0 


84.5 
84.5 
85.5 
87.0 


72.5 
76.5 
7.90 
82.0 
84.5 
86.0 
86.0 
87.0 


77.0 
80 

83 
85 
86 

87 
88 




2 




3 


78.5 


5 


80.5 


7.5 




10 

15 

20 





Methods of speed control for direct-current motors. 1. Arma- 
ture Control, or regulation of the voltage at the brushes by means 
of an adjustable resistance in series with the armature. Recom- 
mended for some service in which speeds lower than normal are 
desired as in controlling the speed of fans, blowers, centrifugal 
pumps, etc. 

2. Field Control, or regulation of the field strength by means 
of an adjustable resistance in the shunt field circuit. Recom- 
mended for service in which speeds higher than normal are desired,, 
as in operating machine tools. 

Armature control. With constant torque, the motor current is 
constant regardless of the speed. Therefore every change in the 



308 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

controlling resistance in armature control produces a correspond- 
ing change in voltage drop in the resistance and a like effect on 
the motor speed. Moreover, the motor speed remains constant 
at any adjustment. The motor output is proportional to the 
product of the torque and speed, and the former remaining con- 
stant, the output must vary with the speed. For example: At 
one-half speed the motor output is one-half that corresponding to 
the same torque at full speed; and since the voltage at the brushes 
must be one-half that of the line, the voltage drop in the con- 
trolling resistance equals the voltage at the brushes. That is, 
one-half the total energy taken from the line is absorbed by the 
resistance and the efficiency of the motor and controller cannot be 
over 50 per cent. 

Constant reduced speeds with varying torque cannot be ob- 
tained by armature control. 

Fans, blowers and centrifugal pumps require an unvarying 
torque at each speed, and with fans and blowers the torque de- 
creases very nearly with the cube of the speed, making this control 
fairly economical. 

For service requiring a continuous operation with full-load 
torque at reduced speeds, adjustment by armature control is very 
inefficient, as much energy is lost in the resistance. 

Field control. With constant voltage at the brushes, the speed 
of direct-current motors varies practically in inverse proportion 
to the change of field magnetism, that is, the weaker the field the 
higher the speed, and vice versa. The field magnetism changes 
with the change of shunt field current, though not always in direct 
proportion thereto. The torque decreases in proportion to the 
decrease in field magnetism; the horsepower output, being pro- 
portional to the product of the speed, and torque remains practi- 
cally constant throughout the entire range of speed. 

With shunt motors, the speed regulation at any given speed is 
good, in fact, practically constant at all loads within the motor 
capacity. This is of especial importance to the operation of ma- 
chine tools and in service of any character where constant speed 
with varying torque is desired. 

Speed control. Starting devises should be provided with au- 
tomatic control so that a failure of voltage, or excessive overload, 
will open the circuit and voltage can not again be impressed on 
the motor or the starter, without connecting the proper resist- 



MOTORS AND CONTROLLING APPARATUS 309 

ance in the circuit. All starters, therefore, should be provided 
with a no-voltage release so that on resumption of the power full 
resistance will be inserted between the line and the motor; and 
either circuit breakers, fuses or magnetically operated switches 
should be provided so that the excessive overload will not damage 
the apparatus. 

Remote control. Two general principles are employed, the 
constant time element and limiting starting current on successive 
steps. 

A. The constant time element is desirable where a smooth even 
acceleration is required as in starting a belt driven load of large 
inertia. 

B. The limiting current method is desirable where starting con- 
ditions require acceleration in steps depending on starting current 
conditions, as with pumps, elevators, and similar service. 

Two types of automatic-control auxiliaries are in general use : 

A. Float type switch, or a float, in an open tank, which closes 
the relay circuit, at either the lower or higher predetermined level, 
and starts or stops respectively the motor, by means of magneti- 
cally operated switches. 

B. Pressure type, or a pressure gauge, in a closed pressure sys- 
tem, which operates in a similar manner at a predetermined lower 
or higher pressure. 

Armature control. A face plate constant speed hand-operated 
starter provided with no-voltage release is satisfactory up to 20 
H.P. capacity. Drum type controllers should be used from 20 
H.P. to 50 H.P. capacities or where frequent starting and stopping 
duty is required. No-voltage release should be provided in con- 
nection with the starters. A fused line switch, circuit breaker or 
similar device should be provided, with the starter, so that the 
circuit will be opened on excessive overload, should the operator 
hold the starting handle on an intermediate resistance point. 

All starters should be arranged to automatically cut in the 
properresistance, once the circuit is opened, either through voltage 
failure or excessive overload, so that the motor and controller will 
be protected on resumption of power. This can be accomplished 
either mechanically or by means of magnetically operated switches, 
electrically interlocked, so it is necessary to move the handle to 
the off position, before again connecting the apparatus in circuit. 

Multiple switch starters should be used above 50 H.P. capaci- 



310 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

ties, arranged with interlocks, so the switches can only be closed 
in proper order, and should be provided with full overload and 
no-voltage release protection. 

The same specifications apply with the addition of proper re- 
sistance steps to operate continuously at reduced speeds. A con- 
stant speed motor is capable of a small increase in speed, say 15 
per cent, by field control, and where necessary, the starters can 
be arranged with an auxiliary control to increase the speed, by 
cutting resistance in series with the shunt field. 

Remote control. Starters, in addition to the use as indicated 
by the name, eliminate the personal element, insuring always the 
same application of the machinery under consideration. 

Acceleration is accomplished by means of magnetically operated 
switches, controlled by relays, and so interlocked that a failure of 
any of the switches will prevent the motor circuit being closed. 
Full overload and no-voltage release should be provided. Either 
face plate or drum type regulators may be used as the master 
switch only controls the relay circuit. 

For remote control speed regulating the master switch should 
be provided with proper latching mechanism, so continuous op- 
eration can be obtained, at reduced speed. Indicating lamps or 
gauges should be provided to show the operating speed. 

Field control. For variable speed the same type of controller 
should be used as specified under the various sub-divisions under 
constant speed motors, with the addition of a field regulating 
rheostat, interlocked with the starter in such a manner that it is 
impossible to start the motor with weakened field. 

ALTERNATING CURRENT MOTORS 

Alternating current motors should be of the induction type, 
with rigid but light construction provided with ample size of 
bearings to be both dust and oil proof. 

Because of the simple mechanical construction, great rugged- 
ness and reliability, squirrel-cage motors should be used for con- 
stant speed service, except where a starting torque of more than 
1 to 1| times full-load torque is required, or where it is necessary 
to keep the starting current below 2\ to 3J times the normal load 
current. If more severe conditions must be met, motors having 
phase-wound rotors should be specified. 

The question of starting current on small induction motors is 



MOTORS AND CONTROLLING APPARATUS 



311 



often given undue prominence. In actual practice it is found that 
even when a large proportion of the total connected load is com- 
posed of small squirrel-cage motors, which are frequently started 
and stopped, that the maximum peak load is but a small per- 
centage increase over the normal load. It is true that squirrel- 
cage motors while starting take from 2\ to Z\ times full-load 
current, but this maximum, as a rule, does not exist more than 
five seconds, and as the motor speed increases the current falls 
rapidly. Two or three times full-load current of a motor, which 
is only 10 per cent of the total capacity of the motors installed, 
is only about 25 or 30 per cent of the total current taken when all 
the motors are operated. 

The commercial speeds and horsepower of 3-phase, 60-cycle, 
220-volt, squirrel-cage induction motors are as follows: 

Horsepower Full load R.P.M. 

1 1700 

2 1135-1710 

3 1140-1720 

5 560-670-859-1130-1700 

7\ 560-670-850-1130-1710 

10 560-675-850-1125-1710 

15 565-680-855-1135-1710 

20 565-675-850-1135-1700 

The standard gear ratio for back-geared motors is approxi- 
mately 5 to 1. Motors with a synchronous speed of 1800 R.P.M. 
are not usually geared above the 3-horsepower size. 

The full-load efficiencies and power factors of the above motors 
are as follows : 





R.P.M. . 


HORSE- 
POWER 


600 


720 


900 


1200 


1800 




PF. 


Eff. 


PF. 


Eff. 


PF. 


Eff. 


PF. 


Eff. 


PF. 


Eff. 


1 

2 

3 

5 

7.5.... 
10 
15 
20 


82 
•80 
80 
84 
83 


81 
84 
84 
86 

87 


81 
80 
84 

85 
84 


83 
83 

84 
86 

85 


83 
83 
86 
86 
85 


85 
85 
85 
85 
85 


78 
81 
86 
85 
90 
89 
91 


84 
84 
84 
84 
85 
86 
87.5 


80 
80 
86 
88 
90 
90 
91 
93 


77 
84 
85 
85 
85 
85 
86 
87 



312 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Auto-starters furnish the most satisfactory means for starting 
squirrel-cage induction motors. They reduce the voltage initially 
impressed upon the motor primary, and simultaneously supply the 
increased current needed for starting, without drawing excess cur- 
rent from the line. For this purpose they are more efficient than 
any form of rheostatic starter, their internal losses are small, and 
it is practically impossible to injure the motor or the starter. 
The essential features are two auto-transformers, by means of 
which the reduction in voltage in two of the phases is obtained, 
and a switching mechanism for connecting the motor primary, 
first across a portion of the auto-transformer taps, and then 
directly across the line. 

The switching mechanism and starter can be enclosed in the 
same iron casing, or the two can be mounted separately. Con- 
tacts of the oil-immersed butt type give the most satisfactory 
operation. 

Motors up to and including 5 H.P. can be thrown directly on 
the line and should be provided with a fused switch. 

Motors over 5 H.P. should have automatic protection. 

The starting current being so much larger than full load current 
fuses or circuit breakers would open at starting, consequently 
starters should be provided with two sets of line leads, one for 
starting and one for running. The starting leads may, or may 
not, be provided with overload protection, according to the start- 
ing conditions, but fuses, or a circuit breaker, must always be 
provided for the running leads. 

Auto-transformers should be provided with no-voltage release, 
and can be provided with overload release when desired. 

Remote control starters. Acceleration can be accomplished in 
two general ways : 

A. Magnetic switches operated through relays, by means of a 
controller. 

B. Mechanically operated auto-transformers with bell cranks or 
rope drive, or where compressed air is available, by means of an 
air cylinder connected to the starting mechanism of the auto- 
transformers. 

Both devices should be provided with full overload and no- 
voltage release. 



MOTORS AND CONTROLLING APPARATUS 313 

PHASE-WOUND INDUCTION MOTORS 

Phase-wound or slip-ring induction motors develop high starting 
torque without drawing excessive current from the line. They are, 
therefore, well adapted for driving machinery, requiring a strong 
starting effort on circuits where close voltage regulation is neces- 
sary, as in starting heavy machinery when the motor is operated 
from a lighting circuit. These motors are especially adapted to 
constant speed service for operating all classes of constant speed 
machinery, such as the operation of hoists, pumps, compressors, 
etc. 

With full-load torque these motors will start and accelerate with 
current not exceeding one and one-fourth times full load. 

The secondary electromotive force is that necessary to drive the 
secondary currents through the windings. It follows that the 
electromotive force required must depend on the resistance of 
these windings. A larger resistance means a larger electromotive 
force for the required current and, therefore, a greater number of 
secondary alternations or a greater slip; the torque being held 
constant, any variation of the secondary resistance requires a 
proportionate variation in the slip. If the slip with a torque is 
10 per cent, for instance, it will be 20 per cent with double the 
secondary resistance, or 50 per cent with five times the resistance. 
The secondary resistance may be in the windings themselves or 
entirely separate from the machine and connected to the winding 
through slip rings. 

This means that the speed of a phase-wound motor can be 
varied below synchronous speed by inserting external resistance 
by means of a proper controller. 

The phase-wound induction motor should be used, therefore, 
when it is necessary to reduce the starting current of the motor 
on account of resultant effect on the lighting system when the 
motors are operated from the lighting circuit; when high starting 
torque is necessary; or when it is desirable to vary the speed of 
the apparatus which is motor driven. 

The commercial speeds and horsepower of 3-phase, 60-cycle 
220-volt, phase-wound induction motors are as follows: 



314 



MECHANICAL EQUIPMENT OP FEDEKAL BUILDINGS 



Horsepower Approximately full load speed 

5 860-1120-1710 

7\ 860-1120 

10 580-690-860-1140 

15 580-690-870-1150 

20 580-690-860-1150 

The full-load efficiencies and power factors of above motors are 
as follows : 





R. P. M. 


HORSE- 
POWER 


600 


720 


900 


1200 


1800 




PF. 


Eff. 


PF. 


Eff. 


PF. 


Eff. 


PF. 


Eff. 


PF. 


Eff. 


5 

7.5.... 
10 
15 
20 


77 
81 
80 


85 
86 
87.5 


82 
82 
82 


86 

87 
87 


80 
78 
81 
83 
83 


85 
85 
86 
87 
86.5 


84 
80 
85 

87 
89 


83 
83 

86 

88.5 
87 


86 

87 


83 

87 



It is preferable in specifications to scale all efficiencies and power 
factors from \ to 1 per cent from those given above, and while the 
best commercial results are desired the specification should not be 
made too rigid. 

CONTROL 

Constant speed, hand starting. Drum type controller with 
auxiliary resistance should be used up to approximately 100 H.P., 
the circuit provided with no-voltage and overload release. The 
starters are only connected with the secondary windings and are 
used to accelerate the speed by short circuiting successive resist- 
ance steps in each phase. All these phases should be intercon- 
nected and grounded to prevent shock to operator. The resist- 
ance may be integral with or separate from the controller of the 
motor. 

Multiple switch-type starters should be used for larger motors, 
the switches being interlocked to provide proper sequence of 
operation. No-voltage and overload release should be provided. 

Variable speed, hand operated. Controllers should be in gen- 
eral the same as above, except equal resistance steps should be 



MOTORS AND CONTROLLING APPARATUS * 315 

provided so the motor can be run continuously at speeds less than 
synchronous. 

Remote-control starting. Magnetically operated switches 
should be used to short circuit successive resistances. The switch 
should be interlocked to insure operation in the proper sequence 
and be provided with full overload and no-voltage release. Face 
plate or drum type controller should be used to operate the relay 
circuit controlling the magnetic switches. 



CHAPTER XI 
VACUUM CLEANING SYSYEMS 

Stationary. The specifications prepared in the office of the 
Supervising Architect for vacuum cleaning systems of the sta- 
tionary type with vacuum producers and separators located on 
permanent foundations, and with a piping system having out- 
lets throughout the building, admit the use of apparatus of both 
the so-called high-vacuum and low-vacuum types, with certain 
restrictions. The high-vacuum type is required to use a 1-inch 
diameter cleaning hose and maintain under test conditions a 
vacuum equivalent to 12 inches of mercury in a separator that first 
receives the dust. The low-vacuum systems are required to use a 
lj-inch diameter hose and to maintain when operated under test 
conditions a vacuum equivalent to 6 inches of mercury in the 
separator that first receives the dust. 

For large buildings which do not contain an electric generating 
plant and in which high-pressure steam is maintained throughout 
the year, consideration is given to the installation of vacuum pro- 
ducers of the steam jet type. Contrary to the generally accepted 
opinion, first class devices of this type are, when provided with 
efficient controlling devices, fully as economical as high-grade 
steam or electrically driven vacuum pumps. In buildings like 
hotels, where cleaning must be constantly going on throughout the 
day, with from one-fourth to one-half the plant capacity in use, 
the jet producers are far more economical in operation than pumps 
of any type. In addition to the relative low cost for maintenance 
and repairs, the steam jet devices have the merit of low first cost, 
simplicity in construction, and economy of space. 

Positive displacement pumps of the piston or double-impeller 
rotary type are permitted under the specifications. 

The reciprocating type of exhauster when fitted with poppet 
type of valve is limited to a piston speed of 200 feet per minute 
in order to insure quiet running. When the rotary type of valve 
is used a piston speed of 300 feet per minute is permissible. Pref- 

316 



VACUUM CLEANING SYSTEMS 317 

erence is given to machines of the lower speed as making for 
longer life and fewer repairs. 

The specifications for the reciprocating type of vacuum pro- 
ducers require strictly first-class workmanship; no pockets or 
clearance spaces are allowed in pistons; piston rings are required 
to fit grooves both in width and depth. Valves are required to 
be placed in heads and the clearance reduced to a minimum. 
The cylinders are required to be jacketed; frames must be of ample 
strength ; cross heads and slides are required and all bearings must 
be lined with anti-friction metal. These specifications are im- 
portant to prevent the use of vacuum producers of less merit. 

Rotary exhausters of the double-impeller type are limited to a 
peripheral velocity of 1100 feet per minute to insure quiet running. 
They are required to be provided with gearing running in oil or 
grease, and must be fitted with water jet for cooling and sealing 
the impellers. At all vacua below 12 inches this type of exhauster 
is more economical than the best reciprocating type; it is practi- 
cally free from wear, and from damage due to foreign substances 
entrained in the air entering the exhauster; the first cost is less, 
and few repairs are required. 

Exhausters of the centrifugal type are admitted by the specifi- 
cations and their speed is limited to a peripheral velocity of 15,000 
feet per minute. Exhausters of this type are required to have 
air-tight casings of aluminum or cast iron, and plain or ball bear- 
ings; and preference is given to machines of the type which are 
provided with vertical shafts so arranged that the weight of mov- 
ing parts equalizes the end thrust. Machines of the centrifugal 
type require special high-speed motors, which are subject to ex- 
tensive repairs. Careful erection is necessary to reduce vibration 
and noise to a minimum. 

This type of exhauster is suitable for low vacuum only. 

All positive displacement and all centrifugal types of exhausters 
installed in Federal buildings are motor-driven. 

In all of the cleaning systems installed in Federal buildings a dry 
separator is required to be placed between the suction lines and the 
exhauster. 

The dry separator must be cylindrical, constructed of sheet 
steel, and provided with cast iron or steel heads. No bags or 
screens are permitted to be installed in this separator. The 



318 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

action of separator must be purely centrifugal and the device 
must intercept not less than 95 per cent of the total dust entering 
same. 

With all positive displacement types of exhauster a second sepa- 
rator is required to be placed between the centrifugal dry sepa- 
rator and the exhauster. The second separator must positively 
remove all dust from the air before it enters the exhauster. The 
second separator may be either of the wet or dry type; and if of 
the latter type may have a bag or core composed of "hush cloth" 
or other suitable material, which must be properly reinforced to 
prevent rupture and so arranged that it may be cleaned without 
dismantling the separator. 

If the second separator is a wet separator it may be cylindrical 
like the dry separators or may be formed in the base of the ex- 
hauster. In either case it must be provided with means for posi- 
tively mixing the air and water and thoroughly breaking up all 
bubbles, and must positively separate the water from the air and 
prevent water and dirt from entering the exhauster. 

With the steam jet or centrifugal types of exhausters this second 
separator may be omitted. 

Separators are required to have a cubic contents of 3 cubic feet 
for each sweeper of plant capacity, for high- vacuum and 4.5 cubic 
feet per sweeper of plant capacity for low-vacuum systems. 

The specifications require that all steam jet and positive dis- 
placement type of exhausters must be provided with a device for 
automatically controlling the vacuum. The control must main- 
tain within certain limits a predetermined vacuum in the dry 
separator. The controlling device may be of the electrical type 
operated by the vacuum in the dry separator to vary the speeds 
of the exhauster and maintain a constant vacuum in the dry 
separator. This type of control when used, requires the motor 
to have special windings so that its speed may be varied from 
one-third to full speed by variation of the strength of shunt field 
only. 

The controller may be of the mechanical type which is intermit- 
tent in action and which closes the suction of the exhauster when 
the vacuum reaches a certain point and opens the suction when 
the vacuum falls 2 to 2| inches below the determined amount. 

The controller may also be of the type that opens the suction of 



VACUUM CLEANING SYSTEMS 



319 



the motor-driven exhauster to atmosphere; or that cuts off the 
steam to the jet type of exhauster and holds the vacuum in the 
separator by means of check valves when the vacuum in the dry 
separator reaches a certain point and closes the air inlet to suction 
of motor-driven exhauster; or that turns on steam to jet type 
when vacuum falls 2 to 2 J inches. 

All of these control systems are required to effect a saving in 
power which is determined by operating the exhauster with all 
hose inlets closed as hereinafter explained under the heading of 
tests. 

Centrifugal types of exhausters do not require any controlling 
device as features inherent in the design thereof tend to produce 
and maintain a constant vacuum within the capacity of the 
machine. 

With all positive displacement exhausters a positive acting 
vacuum-breaker is required to be furnished as a safeguard in the 
event the control fails to operate. 

The power per sweeper required to operate cleaning plants of 
from four to eight-sweeper capacity when operating the full num- 
ber of sweepers on stiff-backed carpets has been determined by 
tests to be as follows : 





SEPARATORS 


POWER PER SWEEPER 


TYPE OF EXHAUSTER 


High vacuum 


Low vacuum 


Reciprocating 


Wet and dry 
2 dry 
2 dry 

Wet and dry 
1 dry 


kilowatt 

2.36 
2.15 
2.06 
2.80 


kilowatt 

2.22 


Reciprocating 


1.98 


Double cam rotary 

Double cam rotary 

Centrifugal 


1.32 
1.80 
1.98 








High vacuum 


Low vacuum 


Steam jet 


250 pounds steam r»er 


200 pounds steam per 




hour 




hour 





The tests were made under the most favorable conditions as re- 
gards power consumption, as the air handled is at a minimum, i.e., 
43 cubic feet per minute for high vacuum, and 60 cubic feet per 



320 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

minute for low vacuum. When cleaning bare floors, walls, re- 
lief work, or pigeon holes, the amount of air passing through the 
cleaning tool is practically equal to that passed by an open hose. 
Capacity tests of sweeping plants are made with hose lines 100 
feet long equal in number to the plant capacity, with ends open 
to atmosphere, under which conditions the high vacuum will 
handle 55 cubic feet and the low vacuum 80 cubic feet of free 
air per sweeper per minute. The power required by the system 
under test conditions above noted is limited by the specifications 
as follows : 

Kilowatts per 
sweeper 

6- to 8-sweeper plants 3| 

3- and 4-sweeper plants 3| 

2-sweeper plants 3f 

1-sweeper plants 4 

The specifications require each bidder to state the size of motor 
he proposes to use, which under test conditions must not be over- 
loaded and must not operate under less than three-quarters of its 
rated power. 

The motor must be constructed in accordance with the standard 
motor specifications prepared by the Supervising Architect; and 
may have shunt, compound, or interpole windings, as the type of 
control requires. 

In addition to the capacity test hereinbefore described a test is 
made to determine the tightness of the system. This is done by 
subjecting the piping to a test under 1\ pounds air pressure, and 
after all outlet valves, separators, etc., are connected the ex 
hauster is operated at the speed specified, and the power required 
to operate exhauster under conditions noted must not exceed the 
following. 

Per cent of power 
required for ca- 
pacity test 

8-sweeper plants 40 

4- and 6-sweeper plants 50 

3-sweeper plants 60 

2-sweeper plants 65 

A test to determine the efficiency of the separators is also made. 
A number of outlets equal to capacity of system are selected, and 
on the floor over an area 50 square feet at each outlet, there is 



VACUUM CLEANING SYSTEMS 321 

spread 6 pounds of dry sharp sand (screened through a 50 mesh 
screen), 3 pounds of wheat flour and 1 pound of powdered charcoal. 
Bare-floor cleaning tools are then attached to outlets, using 50 
feet of hose, and the material is picked up, recovered from the dry- 
separator, spread out again on the floor and again picked up. 
This procedure is repeated a third time. At the conclusion of the 
test the positive displacement exhausters are examined internally, 
and if a trace of any of the above materials is found it is considered 
sufficient cause to reject the separators. 

If the centrifugal or steam-jet type of exhauster is installed the 
quantity of material recovered from the separator is weighed and 
if this be less than 95 per cent of the total material picked up the 
separator is rejected. 

The air piping is standard, black, wrought-iron or mild steel and 
ends of all pipes are reamed. The fittings on air pipes must have 
an inside diameter equal to the pipe bore and may be plain or 
galvanized cast iron drainage fittings, with a radius of not less 
than 3 inches at center line when space conditions permit. Fit- 
tings with less radius are reinforced at point receiving the impact 
of the dust. A standard flange union is used at the base of each 
riser to permit repairs. 

Brass screw-jointed clean-out plugs are provided in fittings at 
turns and at base of each riser, and plugs in 1^-inch line are same 
size as pipe but are 2 inches in all other lines. 

Pipe bends are installed on some lines to reduce the friction. 
Wall outlet sweeper cocks are of the flush type and are pro- 
vided with hinged or screw covers. If latter type of cover is used 
a safety chain must be provided to secure same to the outlet. 
The hinged type must close by its own weight and be provided 
with a rubber disc or ring to make a tight joint. 

Floor outlets are located in a brass box set flush with floor, with 
hinged lid which will not open in a vertical plane and will close by 
its own weight. Sweeper cocks for high-vacuums are all 1-inch 
diameter, and for low-vacuums lj-inch diameter. 

A cabinet containing a complete set of tools is required to be pro- 
vided for each sweeper capacity of the plant, and at least one com- 
plete set of tools for each story of the building. The following- 
tools comprise a set: 



322 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

One 12-inch or 15-inch carpet renovator. 

One 12-inch or 15-inch bare-floor brush. 

One 12-inch or 15-inch wall brush. 

One 4-inch or 6-inch diameter relief clean brush. 

One stair-cleaning brush. 

One 4-inch or 6-inch upholstery brush. 

One corner of crevice cleaner. 

One short stem 1 foot long. 

One long stem 5 feet long. 

One extension stem 5 feet long. 

One 45° handle for floor cleaning. 

One straight handle for woodwork and wall cleaning; or one 
straight handle with detachable swivel. 

All renovators except the stair cleaners and round brushes have 
slots within 15 per cent of the following widths: high-vacuum 
\ inch; low-vacuum \ inch. 

The lips of carpet and upholstery renovators must be so con- 
structed as to prevent injury to the fabric cleaned and reduce 
sticking of renovator face to material cleaned. 

Handles for tools are either cast metal or tubing, and the bore 
of same is required to be uniform size throughout and same size 
as stems. 

Stems are either drawn steel No. 21 gauge or brass tubing 
No. 16 gauge. Stems are 1 inch outside diameter for high- 
vacuum and li-inch outside diameter for low-vacuum. Exten- 
sion stems for wall cleaning are aluminum. 

Carpet renovators are preferred to be cast iron, but either brass 
or aluminum body with an iron wearing face may be used. 

Vacuum breakers are required in the tool handles of high 
vacuum systems, except when renovators are provided with 
inrush slots or other vacuum-reducing devices. 

For each set of tools provided a hose rack is installed, and for 
each rack 100 feet of non-collapsible reinforced hose is supplied, 
which must not weigh over one pound per lineal foot. The hose 
couplings are either screw, slip, or bayonet-lock type, with smooth 
bore of practically same diameter as the hose. Screw couplings 
have ground joints; bayonet-lock joints may have packing washer; 
and slip joints have permanent steel pieces on end of hose and 
brass slip coupling. 



VACUUM CLEANING SYSTEMS 323 

The size of the plant to be installed is based on the floor area 
of the building and as to whether said floor area will be carpeted 
or left bare. 

A stationary plant is not installed in a building where the total 
floor area is less than 50,000 square feet and where the total car- 
peted area is less than 20,000 square feet. 

One operator can clean 3000 square feet of bare floor or 2000 
square feet of carpet per hour. 

The following table is used as a guide in determining the size of 
the plant, and in this connection attention is called to the fact 
that the tendency of engineers is toward the installation of too 
large a plant. 

Number of 
sweep ers in 
Floor area, including basement plant capacity 

51,000 square feet to 100,000 1 

101,000 square feet to 150,000 2 

151,000 square feet to 250,000 3 

251,000 square feet to 400,000 4 

400,000 and up 6 

In preliminary layouts the following space is allowed for the 
reception of the future plant: 

Number of sweepers Space for pump and motor Space for separators 

2-3 3 feet by 9 feet 6 inches 2 feet 9 inches by 5 feet 

4 3 feet by 10 feet 3 feet by 5 feet 

6 4 feet by 11 feet 6 inches 3 feet by 5 feet 

8 5 feet by 14 feet 4 feet by 7 feet 6 inches 

The minimum height allowed for the small plants is 6 feet 6 
inches and for the large plants 8 feet 6 inches. 

A space of 2 feet 6 inches square is allowed for the control board 
and a space of 1 foot 6 inches square for the muffler which is re- 
quired with reciprocating exhausters. The muffler discharge is 
taken into the smoke breeching on stack side of damper; or if 
conditions demand a separate exhaust pipe is run above the roof.. 

If possible, the risers are located so that all parts of building 
to be cleaned may be served with not over 50 feet of hose on any 
outlet. 

The sweeper cock outlets are located in basement, in the post- 
office workroom, and in the lobbies and corridors; occasionally in 
court room, but never in an office room. 



324 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



If conditions require, risers may be so located that 75 feet of 
hose will be required to clean all parts of the building. 

Most of the standard makes of vacuum producers are tapped as 
follows : 



1 sweeper 

2 sweeper 

3 sweeper 

4 sweeper 
6 sweeper 
8 sweeper 



HIGH VACUUM 



Inlet 



inches 

2 

2§ 

3 

4 

5 

5 



Exhaust 



inches 

3 
4 
5 

6 
6 



LOW VACUUM 



Inlet 



inches 

3 

4 
4 
5 
6 



Exhaust 



inches 

3 
4 
5 
5 
6 



The pipe sizes for the systems to be installed in Federal build- 
ings are indicated on drawings. They are given for both the high 
and low-vacuum systems, and are determined by the following 
method : 

A table of equalization of pipes, in which each size is given an 
arbitrary value, is used. To find the size of pipe equivalent of 
any number of pipes of given size, add the values assigned each 
size of pipe, and select the pipe size which is the sum of their 
arbitrary values : 

Pipe size 1" \\" 2" -2\" 3" 4" 5" 6" 

Constant 10 30 60 110 175 380 650 1050 

To determine the size of the risers, assume that only 50 per cent 
of the total number of sweeper outlets on a riser will be in use at 
any one time and allow the equivalent of one 1-inch pipe for each 
outlet in use for high- vacuum and the equivalent of one lj-inch 
pipe for each outlet in use on low-vacuum systems. No riser to 
be less than 2-inch diameter and no branch to a single outlet 
from riser to be made less than lj-inch diameter. 

Example : Assume an 8-story building with eight sweeper out- 
lets on each riser and with four outlets in use on each riser, under 
which conditions for high-vacuum 4 X 10 = 40 which under the rule 
requires a 2-inch riser. For low-vacuum 4 X 30 = 120, which under 



VACUUM CLEANING SYSTEMS 325 

the rule requires a 2j-inch riser. To ascertain the size of mains 
required, start at the last riser on any line and make the main line 
the same size as riser until the next riser is connected to main; 
then make the size of the main equivalent to the risers connected 
thereto until the pipe size is the same as the tapping of the machine 
used. 

Example: Assume a 6-sweeper plant in an 8-story building, 
using a high-vacuum system. The main will start 2 inches and 
when the second riser is connected 60 + 60 = 120, which under the 
rule will make the main 2 J inches. When the third riser is con- 
nected 120 + 60 = 180, and the main will be 3 inches. When the 
fourth, fifth, and sixth risers are added the main will be 4 inches, 
and when the seventh riser is added the main will be 5 inches in 
diameter, which is the size of machine tapping. 

For a low-vacuum system the main will start at 2\ inches and 
when the second riser is connected 110 + 110 = 220, which under 
the rule makes the main 4 inches; the 4-inch size is maintained 
until the fourth riser is connected, 110 X 4 = 440, and the main is 
made 5 inches, which is the size the machine is tapped for. If 
additional risers are added the main would not be increased. 
Whenever possible the machine is located near the center of the 
building and two or more branch mains are used and connected 
together as one main near the separator. Each of the branches 
may be made equal to the machine tapping if the number of 
risers connected to such branch main requires such size under the 
rules stated. The connection from the point of junction of the 
mains to the separator may be same size as the largest branch 
main, or may be increased if desired. 

No account is taken of basement sweeper outlets when calcu- 
lating the size of air mains. The basement branches, and any 
other branches in which material picked up must be lifted, are 
always made \\ inches for high-vacuum and 2 inches for low- 
vacuum. Lifts are to be avoided unless absolutely necessary. 

The above method of calculating the mains is used for all high- 
vacuum systems, and also for all low-vacuum systems when the 
distance from the machine to the end of furthest riser does not 
exceed 400 feet. 

When the distance is greater than 400 feet the size of mains is 
calculated from tables of friction loss, etc., and all pipe sizes are 



326 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

checked so that the velocity of the air in the main will not be less 
than 2000 feet per minute when the plant is operating at full 
capacity. 

SPECIFICATION 

A specification such as is used by the office of the Supervising 
Architect is as follows for a four-sweeper plant: 

VACUUM CLEANING SYSTEM 

General description. The work included in this contract shall 
be the installation of a complete vacuum cleaning system for the 
removal of dust and dirt from rugs, carpets, floors, stairs, furni- 
ture, shelves, walls, and other fixtures and furnishings throughout 
the building, and for conveying said dust and dirt to suitable 
receptacles located where shown, together with all of the neces- 
sary cleaning tools, hose, piping, separators, exhauster, motor, 
etc., as hereafter more fully specified. 

Exhauster. Furnish and erect where shown on drawings Nos. 
V. C. 488 and V. C. 489 an approved air exhauster having a 
nominal capacity for four sweepers at either high-vacuum, 12 
inches, or low-vacuum, 6 inches of mercury, and that shall operate 
without overload under the test conditions hereafter specified. 

The exhauster in all of its details shall be made of the best ma- 
terials suitable for the purpose, and shall be of approved design 
and construction, and may be either of the positive displacement 
(piston or rotary) or of the multistage fan type. 

The piston type of exhauster shall be double acting and so 
designed that the cylinder clearance shall be reduced to a mini- 
mum, or suitable devices shall be employed to minimize the effect 
of large clearance. 

The induction and eduction valves may be either poppet, 
rotary, or semirotary, and shall operate smoothly and noiselessly. 

The piston packing shall be of such character as to be practi- 
cally air tight under working conditions and constructed so that 
it will be set out with its own elasticity without the use of springs 
of any sort. If metallic rings are used, they must fill the grooves 
in which they are fitted, both in width and depth, and must be 
concentric — that is of the same thickness throughout. The joint 
in the ring or rings to be lapped in width but not in thickness 



VACUUM CLEANING SYSTEMS 327 

and if more than one ring is used they are to be placed and doweled 
in such position in their respective grooves so that the joints will 
be at least one-quarter of the circumference apart. 

The piston shall have no chamber or space into which air may 
leak from either side of the piston. All openings into the body of 
the piston must be tightly plugged with cast-iron plugs. 

The piston-rod stuffing box to be of such size and depth that if 
soft packing is used it can be kept tight without undue pressure 
from the gland. If metallic packing is used, it must be vacuum 
tight without undue pressure on the rod. Proper means shall be 
provided for the continuous lubrication of the piston rod. 

The exhauster of the piston type shall be fitted with an ap- 
proved crosshead, suitably attached to the piston rod; machines 
having an extended piston rod for guide purposes will not be 
acceptable. 

The rotary displacement exhauster shall be of the two-impeller 
type. 

Exhausters fitted with sliding blade or blades will not be 
acceptable. 

All parts of the exhauster shall be rigid enough to retain 
their shape when the machine is working under maximum load 
conditions. 

The impellers must be machined all over and must be of such 
shape and size that they will revolve freely and not touch each 
other or the casing (cylinder) in which they are placed, but the 
clearance must be of the least possible amount consistent with 
successful operation. 

The shafts must be of steel with the journals ground to size. 

The journal boxes must be long and rigidly supported by the 
headplates and placed far enough from the headplates to allow 
the placing of proper stuffing boxes on the shafts. 

The shafts must be connected by two pairs of wide-faced steel 
gears, cut from the solid and securely fastened to the shafts. 
The gears shall run in suitable oil-tight gear boxes that shall be 
fitted with adequate and suitable means for lubrication. 

The displacement type of exhaustion may be used for either 
high or low-vacuum system. 

Centrifugal fan type. The centrifugal fan exhauster to be so 
proportioned and constructed as to handle the volume of air re- 



328 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

quired at the specified vacuum with the least possible loss. The 
housing shall be of aluminum or cast iron, made in sections. The 
housing must be air tight. 

The fan wheels to be constructed of aluminum or steel or other 
metal, properly reinforced, and, if cast, must include hub and arms 
complete in one piece. If the fan wheels are built up, they must 
be strongly riveted to cast-iron, steel, or brass hubs or spiders. 

The fan wheels are to be secured to shaft with a feather and set 
screws. 

The shaft of fan exhauster shall be vertical and the wheels so 
mounted that their weight will equalize or partly equalize the end 
thrust, or may be horizontal and end thrust taken care of with 
ball-bearing thrust rings. 

The journal boxes for all of the above-named types of exhausters 
shall be of the design best adapted for the purpose and must be 
fitted with first-class approved continuous lubricating devices, 
either sight feed, ring oiler, or any other kind best suited for the 
work or design of apparatus used. 

Reciprocating piston exhauster shall be provided with the neces- 
sary devices for the removal of the heat generated by friction and 
compression, that shall prevent the temperature of cylinders or 
eduction chambers rising more than 100° F. above the surrounding 
atmosphere after two hours' continuous operation under full-load 
conditions. 

The rotary type of exhaust must be provided with the necessary 
water connections to properly seal and cool the pump. 

Speed. Reciprocating exhauster with poppet valves shall oper- 
ate at an average piston speed not exceeding 200 feet per minute, 
with rotary valves not exceeding 300 feet per minute. 

Rotary exhausters shall not exceed a peripheral speed of 1100 
feet per minute at tips of impeller. 

Centrifugal fans shall not exceed peripheral velocity of 15,000 
feet per minute when running under specified full-load conditions. 

Base plate, foundation, etc. Provide suitable base plate to 
rigidly support the exhauster and its motor as a unit, which shall be 
large enough to catch all drip of water or oil. Provide a raised 
margin and pads for feet of exhauster frame, motor and anchor 
bolts, high enough to prevent any drip from getting into the 
foundation or on the floor. 



VACUUM CLEANING SYSTEMS 329 

Provide suitable foundation of brick or concrete, to which the 
base plate shall be firmly anchored. The foundation shall be 
built on top of the cement floor of the basement, which is not to be 
cut, but shall be picked to afford proper bond for the foundation. 

Construct the foundation of such a height as to bring the work- 
ing parts of the machine at the most convenient level for operat- 
ing purposes. Exposed parts of the foundation to be faced with 
best grade white enameled brick. If the base plate does not cover 
the foundation the exposed top surface is to be finished with 
enameled brick, using bull-nose brick on all edges and corners. 

Drive. The exhauster shall be driven by an electric motor, 
which may be direct connected to the exhauster shaft or be oper- 
ated with a metal-link belt of the noiseless type, or by cut gearing. 
Chain and gearing is to be of ample size and strength for their 
work and must run without undue noise or wear. Means shall 
be provided to take up the slack of the chain belt. Furnish and 
place a suitable metal guard over belt and sprocket wheels that 
shall prevent oil being splashed outside of the base plate and 
prevent clothing being caught. 

If the exhauster is operated through cut gearing the gears 
must be inclosed in an oil and dust-proof case, which shall be 
fitted with means for copious and continuous lubrication of same. 

Finish. The air exhauster and motor and the base plate shall 
be finished in a first-class manner, filled, rubbed down, and 
painted at least one coat at the shop, and after installation shall 
receive two more coats, finishing tint to be as directed. 

Electric motor. Motor to be of such size that when operating 
under test conditions same will not be under less than three-fourths 
nor more than full-load condition. 

Motor to be of standard make, approved by the Supervising 
Architect. 

Motor to be wound for 220 volts direct current. 

Motor armature to be of tooth-core construction, with windings 
thoroughly insulated and securely fastened in place, and must be 
balanced both mechanically and electrically. 

Commutator segments to be of drop-forged copper of high con- 
ductivity, well insulated with mica of even thickness and of such 
texture as will give uniform wear of copper and mica, and shall 
run free from sparking or flashing at the brushes. 



330 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Commutator to be free from all defects and have ample bearing 
surfaces and radial depth as provision for wear. 

Brushes to be of carbon mounted on common rocker arm and 
to have cross-sectional area of not less than 1 square inch for each 
40 amperes of current at full load. Rocker may be omitted in 
event interpolar motor is used. 

Brush holders to be of a design to prevent chattering, with in- 
dividual adjustment in tension for each brush by means of a spring. 

Bearings to be of approved self -oiling type. 

Bidders are required to state in their proposal the rated horse- 
power and speed of motor. 

Insulation resistance. There shall be an insulation resistance 
between the motor frame and the field coils, armature windings, 
and brush holders, and between shunt and series field coils of not 
less than 1 megohm. 

Motor must be capable of standing a break-down test of 1500 
volts alternating current for one minute. 

Efficiency. The efficiencies of motor furnished must not be less 
than — 

One-half load, 83 per cent. 
Full load, 88 per cent. 

Heating. The maximum rise in temperature of any part of 
the motor after a continuous run at full-rated load for a period 
of three hours shall not exceed 90° F. above the surrounding 
atmosphere. 

Shop tests and inspection. The insulation, heating, and efficien- 
cies of the motor shall be determined by actual tests at the shops 
where the motor is constructed under conditions specified. 

The contractor shall give 10 days' notice direct to the Super- 
vising Architect of his readiness for the shop tests of the motor. 

The department reserves the right to waive shop tests or in- 
spections of such portions as may in the opinion of the Super- 
vising Architect be expedient, it being understood that such por- 
tions not fully waived shall be exacted after the installation of the 
apparatus. 

The Supervising Architect reserves the right to waive the shop 
test in the presence of a representative of this office and in lieu 
thereof to require the contractor to submit certified test sheets of 
motor in duplicate. 



VACUUM CLEANING SYSTEMS 331 

Tablet. Furnish and place where indicated a marble tablet not 
less than lj inches thick, supported by a substantial angle-bar 
frame so placed that there will be a space of not less than 1 foot 
4 inches behind the tablet. 

Mount on this tablet one 75-ampere, double-pole, single-break 
knife switch; one double-pole circuit breaker, with auxiliary car- 
bon break and overload release, with range from 25 to 60 amperes; 
and one starting rheostat, with no-voltage release, of proper ca- 
pacity to control the motor. The rheostat and all of the con- 
nections shall be on the back of the tablet. 

The space between the tablet and wall shall be inclosed with a 
removable diamond-mesh grille of No. 10 iron wire in channel 
frame. 

All connections between the tablet and motor are to be made by 
this contractor. 

Two No. 3 feeders are now in place and terminate near the new 
switch tablet which is to be furnished by this contractor. If these 
feeders are not of sufficient length to reach the new tablet, they 
must be spliced to new feeders, the splice being made in a junction 
box. 

All wires are to run in standard steel conduit, except those that 
are so short as to be self-supporting, and these are to be cord 
wrapped or otherwise protected. No wire smaller than No. 12 to 
be used. 

All material and workmanship to be strictly first class. Elec- 
trical work must show an insulation resistance of at least 1 meg- 
ohm, and to be in strict accordance with the latest edition of the 
"National Electrical Code." 

Automatic control. Suitable means shall be provided in con- 
nection with the motor of reciprocating or rotary exhausters that 
will maintain the vacuum in the separators within the limit of the 
machine at point found to be most desirable, irrespective of the 
number of sweepers in operation. 

This controller may consist of an automatic device, mounted 
on the tablet hereinbefore specified, to change speed of motor con- 
trolled by the variations of the vacuum in the system. If this 
method of regulation is used, the motor shall be provided with 
special windings that will permit a speed variation of from one- 
third full speed to full speed by variation of shunt field only, 
without undue sparking at the brushes. 



332 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

In lieu of above method of control suitable means may be pro- 
vided in the exhauster, or as an attachment thereto, which will 
automatically throw the exhauster out of action by admitting 
atmospheric pressure to the exhauster only, but not to the system; 
or that shall cause suction from the system to cease whenever the 
vacuum in the separators rises above the point considered desir- 
able, and throw the exhauster into action when the vacuum falls 
below the established lower limit. 

Drawings. Contractor will be required to submit for approval, 
after award of contract, drawings in triplicate showing exhauster, 
motor, separators, connections, and type of control, in detail. 

Said drawings must be approved by the Supervising Architect 
before any of the work is installed. 

Vacuum breaker. In addition to the controlling devices above 
specified, if reciprocating or rotary exhauster is used, there shall be 
placed in the suction pipe to the exhauster an approved positive- 
acting vacuum breaker having opening equivalent to the area of 
1-inch diameter pipe and set to open at 12 inches for the high 
vacuum system. 

If centrifugal fan-type exhauster is used, it must be designed so 
that the maximum vacuum shall not exceed 6 inches of mercury 
and no vacuum control or vacuum breaker will be required. 

Dust separators. Furnish and place at some convenient point 
between the vacuum mains and the exhauster one dry separator 
having a volume of not less than 12 cubic feet for a high or 18 
cubic feet for a low-vacuum system. 

If a displacement type of exhauster is installed, there shall be 
furnished an additional separator to be placed between the first 
separator and the exhauster cylinder, which may be either wet or 
dry, as desired, and may be contained in the base of the machine 
or consist of a separate tank. 

If centrifugal type of exhauster is installed, but one separator, 
and that a dry separator, will be required. 

Separator tanks shall be constructed with steel shells, with 
either cast-iron or steel heads, and be fitted with suitable bases 
or floor stands for support. 

The interior arrangements of the dry separator first receiving the 
dust shall be such that no part of same will receive the direct im- 
pact of the dust. No cloth bags nor metal screens will be per- 



VACUUM CLEANING SYSTEMS 333 

mitted in this separator. It must be so constructed that it shall 
intercept not less than 95 per cent of the dust entering same. 

If two dry separators are used, the second separator must be 
arranged so that none of its appliances are liable to be ruptured 
by air currents or of being di;awn into the piping or exhauster, 
and the arrangment of same must be such that the separator can 
be easily cleaned without dismantling same. 

Wet separators, whether separate from or integral with the base 
of the machine, must be provided with an attachment which will 
positively mix the air and water, thoroughly break up all bubbles, 
separate the water from the air, and prevent any water entering 
the exhauster cylinder. 

If wet and dry separators are used in combination, suitable 
means must be provided to automatically equalize the vacuum 
between them upon the shutting down of the exhauster. 

The separators must be provided with suitable openings for 
access to the interior for inspection and cleaning, and the interior 
arrangement of the separators must be such that they may be 
readily cleaned without dismantling. 

All parts of the wet separator tank not constructed of non- 
corrosive-metal must be thoroughly tinned or galvanized both 
inside and outside. The interior of the wet separator formed in 
base of exhauster shall be painted with at least two coats of 
asphalt varnish or other paint suitable to prevent the corrosion of 
the same. 

Separators must be provided with all necessary valves or other 
attachments for successful operation, including a sight glass for the 
wet separator, through which the interior of same may be ob- 
served, and a 30-inch iron case mercury column attached to the 
dry separator first receiving the dust. 

Wet separator shall be connected to the water-supply main and 
to sewer, which pipes are in place in the machine room, as directed. 
A running trap with clean out shall be installed in the waste line 
between separator and sewer. 

Piping. The vacuum mains shall be installed as indicated and 
noted on drawings. 

The pipe size indicated on the drawings, inclosed in circles, are 
to be followed for a high-vacuum system and the pipe size inclosed 
in squares are to be followed for a low-vacuum system. No in- 
crease or decrease in these pipe sizes will be allowed. 



334 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

Pipes. All pipe conveying air is to be standard, black, wrought 
iron, or mild steel, screw-jointed pipe, and is to be smooth inside, 
free from dents, kinks, fins, or burrs. Ends of pipe to be reamed 
to the full inside diameter and beveled. Bent pipe to be used in 
mains where necessary. 

Care must be taken in erecting pipe to maintain as nearly as 
possible a smooth, uniform bore through all pipe and fittings. 

Waste and water pipe, in connection with wet separator and 
jacket (if used), except waste pipe below basement floor to be 
standard galvanized wrought iron or steel, screw-jointed pipe, free 
from burrs. Waste pipe below the basement floor is to be best 
grade, " extra heavy" cast-iron pipe, with lead-calked joints. 

Fittings. All fittings to be tough, gray cast iron, free from blow 
holes or other defects; smooth castings in all cases. 

All fittings on vacuum lines must have inside diameter through 
body of same size as pipe bore,- and all fins, burrs or rough places 
must be removed. 

Fittings on vacuum lines are to be black or may be galvanized. 

Where space permits, all tees and elbows, must have a radius at 
center line of not less than 3 inches. 

All fittings having less than 3-inch radius must have the thick- 
ness of metal on sides receiving the impact of the dust increased 
50 per cent above standard thickness. 

A standard cast-iron flange union is to be provided on the 
connection to each riser near the base. 

Fittings on water lines to be standard galvanized beaded 
fittings. 

Fittings on waste line above basement floor to be galvanized, 
recessed, screw-jointed drainage fittings, and those below base- 
ment floor to be " extra heavy" cast iron with hub joints. 

Horizontal overhead pipes to be supported with substantial pipe 
hangers spaced not more than 10 feet apart. 

Where exposed pipes pass through walls or floors of finished 
rooms, they must be fitted with cast-iron, nickel-plated plates. 

Clean-out plugs. Brass screw-jointed clean-out plugs are to be 
provided in lines at all turns where indicated on the drawing. The 
clean-out plugs to be 2-inch diameter, except in the l^-inch lines, 
where clean-outs are to be same diameter as the line. 



VACUUM CLEANING SYSTEMS 335 

Exhaust connection. Exhaust pipe from the exhauster is to be 
run up to the basement ceiling and along same into the vent shaft 
and up same to attic and through the roof, as indicated. The 
opening in roof is to be flashed with 6-pound sheet lead and pro- 
vided with counterfLashing. 

The exhaust pipe is to be fitted with an approved firstclass 
exhaust muffler not less than 12 inches in diameter and 6 inches 
high, closely riveted and constructed of galvanized iron not less 
than J-inch thick, and in event an exhauster requiring lubrica- 
tion is furnished this muffler is also to be arranged so that it will 
also be an efficient oil separator. Drip connection to be arranged 
at bottom of muffler. 

Sweeper outlets. The following number of outlets are to be 
provided: Basement, three; first story, six; second story, three; 
third story, three; fourth story, three; fifth story, three; sixth 
story, three; attic, three. 

The sweeper outlets may be fitted with hinged screw covers or 
caps with rubber gaskets. If screw cover is used, same is to be 
provided with a safety link, brass, nickel-plated chain. If hinged 
type of outlet is used, same is to be arranged to be self-closing 
when hose is removed. 

Outlets cOming through finished walls or partitions are to be 
flush pattern. 

Outlets on risers run exposed against walls are to be set close 
up against bead of fittings. 

If contractor desires to use other form of connection than above 
described, which is equally satisfactory, same must be submitted 
to the Supervising Architect for approval after award of the 
contract. 

Tool cases. Furnish eight approved hardwood cabinet- 
finished cases for cleaning tools. Each case to be made as light as 
possible and of convenient form for carrying by hand and pro- 
vided with a complete set of cleaning tools, each securely held in 
its proper place and fitted with lock and key, clamps, and con- 
veniently arranged handles. 

In this specification the word " renovator" is used to mean 
that portion of the tool which is in contact with the surfaces 
cleaned; the word "stem," that portion connecting the renovator 



336 MECHANICAL EQUIPMENT OP FEDERAL BUILDINGS 

and handle, and the word "handle," that portion held in the hand 
and to which the hose is attached; the word "cleaner" is used to 
mean a complete cleaning tool. 

Cleaning tools, etc. The following cleaning tools are to be 
furnished for each case: 

One renovator not less than 12 inches nor more than 15 inches 
wide, for cleaning carpets. 

One renovator not less than 12 inches nor more than 15 inches 
wide, for cleaning bare floors. 

One brush renovator not less than 12 inches nor more than 15 
inches wide, for cleaning walls. 

One dusting brush renovator not less than 4 inches nor more 
than 6 inches in diameter, for cleaning relief work. 

One brush renovator suitable for stair cleaning. 

One upholstery cleaner not less than 4 inches nor more than 6 
inches wide for cleaning upholstery furniture. 

One corner and crevice cleaner. 

One short stem about 1 foot long. 

One long stem about 5 feet long. 

One extension tube about 5 feet long. 

One 45° handle for floor cleaning. 

One straight handle for woodwork and wall cleaning. 

Both kinds of handles to be provided with couplings for hose 
and stems to be provided with hand-operated full-area roundway 
valves. The cut-off valve must be easily operated and be indi- 
cating and when closed be practically air tight. All movable 
parts that are in contact must be arranged so as to be protected 
from dust and from wear from this cause. 

The renovators for carpets, bare floors, walls, and relief work 
to be arranged with adjustable swivel joint, so that same can be 
set at an angle with stem from 45° for regular use to an angle of 
about 80° for use under or back of furniture and other similar 
places. This movable joint can be made so that it can be easily 
adjusted and firmly set and held in place, or so arranged that lips 
of cleaning tool will always remain in contact with surface cleaned, 
and constructed so that fitted surfaces are not exposed to dust, 
and the air current when deflected to impinge only upon surfaces 
which are of heavy metal and where such wear as occurs will not 
affect the operation and handling of the tool. 



VACUUM CLEANING SYSTEMS 337 

In lieu of the above adjustable joint in the renovators them- 
selves special couplings, one for each stem, may be furnished in 
addition to the straight couplings, which can be used in connection 
with the renovator mentioned so as to bring the latter to the 80° 
angle required. 

All renovators, stems, and handles are to be as light as is con- 
sistent with strength and ability to withstand cutting action of 
dust. 

All renovators, except round and stair brushes, are to have 
slots of the following widths: 

For high-vacuum system, \ inch wide. 

For low-vacuum system, \ inch wide. 

A variation not exceeding 15 per cent in width of slots as given 
above will be allowed on carpet renovators. 

A variation of 25 per cent increase will be allowed on brush 
renovators. 

If renovators, with air-intake slots, or other form of vacuum 
reducer, or short-circuiting opening, are used, the area of the 
main slot may be increased 20 per cent. The area of intake 
opening or slot is not to exceed 10 per cent of the net area of 
main slot. 

The lips of carpet renovators and upholstery cleaner to be of 
such proportions, and form as will prevent injury to the fabric, 
and such width as will reduce to a minimum the sticking of 
renovator face to the material being cleaned. 

An approved J-inch diameter finished-brass, nickel-plated, 
positive-acting vacuum breaker, with an adjustable brass spring, 
inclosed within a removable cap, is to be provided in the handle 
of a high-vacuum system, and must be connected to handle by 
J-inch diameter standard screw-pipe connection so as to be 
removable for cleaning, etc. In event air-intakes slots or other 
vacuum-reducing devices are used in the high-vacuum system, 
the vacuum breakers in the tool handles may be omitted. In 
event centrifugal exhauster which will not produce more than 6 
inches of vacuum is used, the vacuum breakers in tool handles 
may be omitted. 

Handles to be cast metal or combination of cast metal and 
tubing. 

Stems to be not less than 1 inch outside diameter for high- 



338 MECHANICAL EQUIPMENT OF FEDEEAL BUILDINGS 

vacuum system and li-inch outside diameter for low-vacuum 
system. Air passages in handles and swivels to be same diameter 
as inside of stem. 

The handles are to have long-radius curves, and connections 
are to be made without shoulders or projections in the bore against 
which dust can strike. Parts of handles receiving dust at change 
of direction are to have ample metal to allow for cutting effect of 
dust. 

Stems to be drawn-steel or brass tubing, not less than No. 21 
United States standard gauge thick if steel and not less than No. 
16 Brown and Sharpe gauge thick if brass. 

Carpet renovators to be made preferably of cast iron, as light 
as possible, or may be made of cast brass with iron wearing face. 

All brushes to be of substantial construction, with best quality 
bristles set in close rows and as thick as possible, skirted with 
rubber, leather, or chamois skin so that all air entering renovator 
will pass over surface being cleaned. 

All renovators and brushes must be provided with proper rub- 
ber or other approved buffers to prevent marring the woodwork. 

Upholstery cleaners are to have inlet slots or openings of such 
size and form as to absolutely prevent drawing in loose covering 
of furniture. 

Upholstery and corner cleaners are not to be arranged for use 
with stems and handles, but are to have their own handles perma- 
nently attached, and be provided with hose couplings, and with- 
out valves and vacuum breakers. 

All metal parts of renovators, stems, and handles are to be fin- 
ished, and all except aluminum parts nickel plated. 

Hose racks. Furnish and properly secure in place, where 
directed, one hose rack in basement, first, second, third, fourth, 
fifth, sixth, and attic stories (eight racks in all). 

The racks to be constructed of cast iron, galvanized or enamel 
finish, and each rack to be suitable for holding 75 feet of hose of 
required size. 

Hose. There must be furnished with each hose rack 75" feet 
of non-collapsible hose in three 25-foot lengths. 

Hose to be not less than 1 inch inside diameter for high-vacuum 
system and not less than lj-inch inside diameter for low-vacuum 
system, and must be smooth inside and outside. 



VACUUM CLEANING SYSTEMS 339 

The hose to be best quality rubber hose, reinforced in best man- 
ner to absolutely prevent collapse at highest vacuum obtainable 
with the exhauster furnished and to prevent collapse if stepped 
on. Weight of hose to be not over 16 ounces per linear foot. 

Couplings for hose to be either screw, slip, or bayonet-lock 
type, with smooth bore of practically same diameter as inside of 
hose. The couplings to have least possible projection outside of 
hose dimensions and be well rounded, so as not to injure floors, 
doors, furniture, etc. 

Screw couplings to have ground joint; bayonet joints may 
have packing washer, and slip joints to have permanent steel T 
pieces on ends of hose and brass slip coupler. All ends of hose 
couplings to have outside ferrules securely fastened in place. 
Simple conical slip joints slipped into ends of hose without fer- 
rules will not be acceptable. 

Samples. The successful bidder, after award of contract, if 
required by the Supervising Architect, must submit to the Super- 
vising Architect for approval one cleaning-tool case supplied with 
full set of cleaning tools, one of each kind of outlet, and one piece 
of vacuum hose, 12 inches long, supplied with coupling at one 
end. 

Tests. The contractor is to make tests hereinafter described in 
the presence of the Department's representative and must fur- 
nish all the labor necessary to make said tests. 

Operation test. After the complete installation of the appa- 
ratus, a capacity test of the exhauster shall be made. Four 
outlets shall be selected by the Department's representative, but 
not more than two on any one riser, and to each shall be at- 
tached 100 feet of hose, of size required by the system, with end 
open. To be acceptable, this test must show that the exhauster 
shall maintain the specified vacuum when running at or under the 
specified speed, and the power consumed shall not exceed 14 
kilowatts. 

To test the tightness of the system and the effectiveness of the 
vacuum control, the exhauster shall be run with all outlets closed, 
and the power consumed shall not exceed 50 per cent of that at 
full load. 

Test of cleaning tools. The plant shall be operated by the 
contractor in presence of the Department's representative, and a 



340 MECHANICAL EQUIPMENT OF FEDEKAL BUILDINGS 

test made of each kind of cleaning tool furnished. The tool 
shall be attached to a 50-foot length of hose attached to an out- 
let selected by Department's representative, and under normal 
working conditions each tool must satisfactorily perform the work 
for which it was designed. Dust and surfaces to be cleaned shall 
be furnished by the contractor. 

Test of separators. At each of four points, near four outlets 
selected by the Department's representative (not more than two 
outlets on any one riser), the contractor shall furnish and spread 
on the floor, evenly covering an area of approximately 200 square 
feet for the four outlets, or 50 square feet for each outlet, a mix- 
ture of 24 pounds of dry, sharp sand that will pass a 50-mesh 
screen, 12 pounds of fine wheat flour, and 4 pounds of finely 
pulverized charcoal. 

Fifty feet of hose of size required by the system used shall be 
attached to each of the four outlets, and the surface or surfaces 
prepared for cleaning shall be cleaned simultaneously by operators 
provided by the contractor, until all of the sand, flour, and char- 
coal has been taken up, when the exhauster shall be stopped and 
the dirt removed from the dry separator and spread on the floor 
again, and the operation of cleaning repeated until the mixture 
has been handled by the apparatus four times. If, after thor- 
oughly flushing the system, at completion of the above run, any 
dust or mud is found in the cylinder, ports, or valves chambers 
of the displacement exhauster, or if less than 95 per cent of the 
dirt removed is found in the dry separator of the centrifugal ex- 
hauster, it shall be deemed sufficient ground for the rejection of 
the separators. 

Painting. After the completion of the specified tests, all ex- 
posed galvanized-iron or tinned work in connection with this 
apparatus, not specified to be otherwise finished, shall be primed 
with paint suitable for galvanized or tinned surfaces, and then 
given two additional coats. Machinery shall be painted as 
already specified, and all other work shall be given finishing 
tints as selected or approved by the custodian. Black iron shall 
be primed with a coat of red lead and linseed oil. 

Portable apparatus. For Federal buildings containing less than 
50,000 square feet of floor area, a portable vacuum cleaner com- 



VACUUM CLEANING SYSTEMS 341 

plying with the following specifications is supplied at a cost of 
about $125.00. 

Vacuum producer shall be of rugged construction with well- 
proportioned parts. It must be capable of displacing not less than 
50 cubic feet of free air per minute at the end of not less than 15 
feet of cleaning hose, and must produce a vacuum when outlet is 
closed of not less than 22 inches of water. 

Motor shall be of standard make, of ample power to drive 
vacuum producer. 

The maximum power consumption when operating either with 
open hose or with renovator on carpet shall not exceed 360 watts. 

The motor must be fitted with a suitable device to permit same 
to be started with a 10-ampere fuse in the circuit. 

Dust separator shall be constructed of metal and be so ar- 
ranged that it can be easily cleaned. The capacity and arrange- 
ment of dust separator shall be such that at least one peck of 
dust may be picked up and the machine still do effective work and 
the separator intercept all dust and dirt without cleaning the dust 
separator. 

The vacuum producer, motor, and dust separator shall be 
mounted as a unit. No wood shall be used in any part of this 
unit. The combined unit shall be mounted on wheels or casters 
and fitted with suitable handles, and shall not weigh more than 
80 pounds. 

The following equipment to be furnished with the cleaner: 

25 feet flexible reinforced new code No. 14 double conductor 
with Edison screw attachment plug. 

Not less than 15 feet of reinforced rubber- lined cleaning hose 
not less than lj-inch inside diameter. 

One brass or aluminum tubular handle not less than 4 feet long. 

One extension tube 5 feet long. 

One carpet renovator with cleaning slot not less than 8 inches 
long by | inch wide, with cast-iron wearing face. 

One hard- wood floor tool. 

One floor brush. 

These may be arranged to be attached to carpet ranovator if 
desired, and shall have cleaning slots with areas equal to or 
greater than that of carpet renovator. 



342 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

One wall brush not less than 5-inch diameter. 

One upholstery tool with not less than 3-inch cleaning slot. 

One corner cleaner. 

One blowing nozzle. 

All renovators to be made of aluminum or of brass, the former 
being preferred, and all parts except aluminum to be nickel- 
plated. 

The foregoing specification for portable cleaning apparatus was 
used by the Department until October, 1911, at which time the 
Bureau of Standards undertook the testing of these devices for 
the Treasury Department with a view to selecting the best ap- 
paratus. When the tests are completed a new specification will 
be issued. 



CHAPTER XII 

OPERATING DATA 

There are few engineers who have jurisdiction over the design, 
construction, and operation of mechanical and electrical equip- 
ment of buildings, and this lack of intimate contact with the 
actual operating side of plants is a severe handicap to those who 
are not so fortunate, especially when they are called in to defend 
their recommendations for installation of isolated power plants 
for buildings or industrial establishments, for the reason that their 
information on the subject of plant operation is purely theoretical 
and they have no bona fide records of their own to back up their 
calculations. 

It is also true that only a few operating engineers are pro- 
vided with means for accurately determining the coal and cur- 
rent consumption rates of the apparatus under their charge. 
The great majority are densely ignorant regarding the distribu- 
tion of the steam generated in the boilers to the different portions 
of the equipment, i.e., the electric generating plant, the heating 
apparatus, etc.; and consequently they have no records to produce 
and have only a hazy idea of the situation when confronted by a 
good contract agent from the central station in an argument for 
or against shutting down the electric generating plans under their 
charge. 

The office of the Supervising Architect is particularly fortunate 
in that it has exclusive jurisdiction over the design, construction, 
repair, and operation of the various buildings that it erects, and 
also has exclusive jurisdiction over the personnel of the operating 
forces, as well as over the purchase and use of all the supplies, 
etc., required for the various buildings. That this situation is 
correct and logical is borne out by the extraordinary economies 
that have been effected since steps were taken to place all these 
responsibilities under one technical bureau instead of entrusting 
them to several related or nonrelated bureaus, as was previously 
the custom in the Treasury Department, and as is still the custom 

343 



344 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

in connection with school buildings, etc., in various cities in this 
country. 

In order to obtain data upon the operation of Federal buildings 
under control of the Treasury Department, records are kept in 
some detail, especially in the larger buildings, and these records 
and data are studied, compared, and used as guides in the design 
of new projects. 

All of the important buildings containing electric generating 
plants are equipped with coal scales, steam flow meters, water 
flow meters, C0 2 machines, etc., and the chief operating engineers 
are provided with daily report blanks covering the coal consump- 
tion, ash removal, steam consumption of electric generating plants, 
etc. A few samples of the actual reports follow: 






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349 



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CO 

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350 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



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OPERATING DATA 



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352 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 




<V <V <D 

+2 ■+= -+^ 

d & & 



OPERATING STATISTICS FOR CERTAIN LARGE GOVERNMENT BUILDINGS 




Since the preparation of the foregoing table the electric generating plants in Brooklyn and New YorkCity 

have been shut down, and current is now purchased from the Edison Company, with the result o 

s^vTng "Brooklyn of approximately $8,000 per year, and in New York City of approximately $12,000 per >ear. 



OPERATING DATA 353 

These monthly reports from the large buildings are turned over 
to one of the mechanical and electrical engineers of the office, 
who analyzes them, compares one with another, and calls to the 
attention of the chief mechanical and electrical engineer any 
matters that need attention. 

Each year these monthly reports are tabulated for ready com- 
parison, as illustrated by the table facing page 352. 

The Department holds no brief for the isolated plant versus 
the large central plant, but analyzes each individual building on 
its merits and chooses the most economical course in the matter 
of supplying electricity and light. 

To compete with the large central plants it is absolutely neces- 
sary to install engines and generators of the highest economy con- 
sistent with a reasonable first cost, and this has led to the adop- 
tion of the high-speed non-release Corliss type of 4-valve engine 
with a low percentage of clearance and close regulation, because 
electric elevators are operated from the same bus-bars as the 
lighting system, and no flickering of the lamps is tolerated. The 
engines and generators are purchased on the valuation system, 
which means, in effect, that the Government is willing to make a 
substantial investment in steam or current producing apparatus if 
it can be demonstrated by test that the savings per annum of the 
costly apparatus will pay a dividend of 13 per cent on the addi- 
tional investment which is always required when the first cost of 
an economical steam engine is compared with the first cost of an 
engine that is not economical and is marketed and exploited merely 
as an engine. 

With the foregoing data at hand the actual cost of operating 
the electric generating plant in a building is known at once, and the 
question of purchasing current and shutting down the plant can 
be discussed intelligently. It may be stated in passing that the 
actual cost records are very disconcerting to the central station 
solicitor, who generally proceeds to assign values to steam con- 
sumption of engines, water evaporating capacity of boilers, etc., 
with considerable disregard of the facts as found in Federal 
buildings. 

It will be noted that the cost of labor in connection with the 
buildings given above as examples is very high as compared with 
the cost of labor in commercial plants, and it is worthy of note that 



354 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



by careful operation and close supervision it has been possible to 
compete with the large central stations except where certain influ- 
ences have made the labor item outrageously excessive. In the 
plants which have been shut down in recent years the cause of 
the change has been that the engineering employees have over- 
reached themselves in the matter of hours of labor, rates of pay, 
etc., coupled with the fact that the plants themselves were old and 
generally low in all-around efficiency. 

The central stations are each year making lower rates and ap- 
proaching the point where the cost of purchasing current will be 
equal to or less than the cost of operating the isolated plants, and 
it behooves those interested in the maintenance of an isolated 
plant to keep up to date and effect every possible economy. 

The following table is introduced to give an idea of the annual 
consumption of electricity for power and light in certain Federal 
buildings. It is interesting to compare the current consumption 
in Federal buildings (which are 24-hourbuildings) , with commercial 
buildings as reported by the Wisconsin Public Service Com- 
mission : 



CLASS OF BUILDING 



Churches 

Farms 

Laundries 

Lodge halls 

Schools 

Residences 

Theatres 

Offices 

Livery stables 

Stores 

Hotels 

Signs 

Bowling alleys 

Depots 

Saloons 

Industrial establishments 
Restaurants 



k.w.h. per annum 

per k w. op full 

connected load 

(lighting only) 



101 
183 
185 
194 
236 
239 
367 
400 
402 
471 
505 
551 
809 
937 
955 
1069 
2209 



OPERATING CHARACTERISTICS OF CERTAIN LARGE AND SMALL FEDERAL BUILDINGS 



Bu,/.oiNQ 
NAME 

ch/caoo, P. O- 


Cu. Fr. 

CONTENTS 

il, 564, ooo 


>S<?. Fr. of Lighted Area 


No. of- Employcs 


Se). Ft. 

PEFi 

EntPLoret 
/57 


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PoW£/? 


r °W- Light ^w Powr/f 1 




■ f;,°- ubbu °^ eir 

359,750. £2,350 377.30C 


Tot 1 *// 

760,ooo 


P.O. 


Genenl 


7e,M 
4830 


F.ty. 
Co/HiecA*! 
360 


Warfs 
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0-47 


K.W- AW.//, per 
Demur* ' Annum 
3/0 /, zoo, 000 


K.WJ/./xr KH/J/.per 

Sq. Pr 1 . Enyleyee 

1.58 Z48. 


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Wotor ti.p. 

Zoonec/ecl 

925 


jDemonat 
J4o 


K.WM/xr KW.H./HP. K.W.//./AW. cen- 
/tnnum Ptr /inm/m nec/ea 1 /Mptr/fn, 
335,000 362 487 


K, W- K.WM./Ar.rV. Co 
Ozmonc/ ncc/aS/y.perJn, 
420 /*e« 




/>oy 
/£3o 


Nioh) 
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400 


3,333 


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9.1 




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8, 334.ZOO 
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570,000 
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8,0 

to. 7 

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343,000 
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580 
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678 
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107 ~~- 

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1,7 70 

Z,0BO 

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1,740 




Average 


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304,500 










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767 


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19,323 


27, 870 


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11.8 


0.43 




II. 7/1 


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104 


990 


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413 




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5l5,ooO 


3,31/ 


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17,776 


23, 030 


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10.7 


0.4 7 




4,302 


0.19 


78 


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2,094 


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55 


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3.3 


0.46 




ZO, 268 


0-94 


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5/0, OOO 


2,774 


J.7S4 


20, 532 


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32 


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96 


261 


13.3 


0.53 




11, 362 


0.45 


119 


653 


2.3 


20 




2.776 


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» Concilia ' Mec/i/ne 4 War 











OPERATING DATA 



355 



FEDERAL BUILDINGS 



Small buildings up to 250,000 cubic 
contents 



250,000 to 500,000 cubic contents... 
500,000 to 1,000,000 cubic contents. 
1,000,000 to 10,000,000 cubic con- 
tents 



K.W.H. PER ANNUM 
PER K.W. FULL CON- 
NECTED LIGHTING 
LOAD 




K.W.H. PER ANNUM 

PER H.P. OF FULL 

CONNECTED POWER 

LOAD 



350 
(all stamp cancel- 
ling machines) 
160 
300 

400 



The foregoing data are extremely valuable in estimating the 
operating characteristics of a new building which is being designed, 
at which time it is essential that the maximum demand, full con- 
nected load, annual K.W.H. consumption, heating requirements, 
labor force, etc., be accurately determined, in order that an in- 
telligent comparison may be made with the rates quoted by the 
local electric company to see whether the installation of an isolated 
electric light plant would be justified. 

It may be stated roughly that the full connected power and 
lighting load will not exceed lj watts per square foot of the en- 
tire building; that the maximum demand will not exceed 45 per 
cent of the full connected lighting and power load; and that the 
electric current consumption per annum for power and light will 
not exceed 2 K.W.H. per square foot of floor area in a modern 
building with ample and well-placed windows. 

Generally speaking, an isolated plant begins to be feasible in a 
Federal building where the full connected load is not less than 150' 
K.W. or more and where the annual current consumption is not 
less than 200,000 K.W.H. or more per annum and the cost of cur- 
rent from the central station does not exceed 4 cents per K.W.H.. 

In commercial buildings, an authority states that in and around 
New York City where the cost of purchased current will ap- 
proximate 5 cents per K.W.H. an isolated plant should be given 
consideration when the annual current consumption is 60,000 
K.W.H. or more. 

A leading mechanical and electrical engineer of New York City, 
has stated that in a given building where there are two or more 
electric elevators and 1000 or more lighting sockets (50-watt rat- 



356 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



ing) an isolated plant becomes a possibility when the cost of pur- 
chased current is 5 cents per K.W.H. or greater. 

The accompanying table represents the operating characteris- 
tics of a large number of Federal buildings in Washington, D. C. 
These data were gathered in connection with a report made by 
the writer for the establishment of a central heating, power, and 
lighting plant to serve the buildings noted. Based on the re- 
port an appropriation of approximately $1,500,000 was made by 
Congress to carry out the project. 

Certain of the older Federal buildings in the larger cities were 
not originally provided with isolated power plants, and a few years 
ago the writer detailed an able engineer to visit these buildings and 
determine on the ground, after full conference with the local 
public service officials, whether the installation of isolated plants 
would be justified. In one notable instance the situation was 
especially favorable, and the engineer reported as follows: 

The following data were obtained from records and conditions at the 
building to form a basis of data in considering the installation of a plant: 
Total wattage of lamps is 377,000. 
Total K.W. rating of motors is 700. 
Total floor area is 660,000 square feet. 
Present coal and current consumption. 



July 

August 

September 

October 

November 

December 

January 

February 

March 

April 

May 

June 

Summer months 
Winter months 

Totals 



CURRENT IN K.W.H. 



Summer 



98,840 
100,340 
105,860 



109,420 
106,430 
116,590 



637,480 



Winter 



117,240 
115,590 
127,080 
123,970 
125,800 
125,800 



735,480 



637,480 
735,480 



1,372,960 



TONS OF COAL 



Summer 



323.790 
309.350 
319.970 



406.479 
316.392 
269.649 



1,945.630 



Winter 



417.835 
538.427 
537.414 
837.000 
694.720 
670.715 



3,696.111 



1,945.630 
3,696.111 



5,641.740 



OPERATING CHARACTERISTICS OF CERTAIN FEDERAL BUILDINGS IN WASHINGTON, D.C. 



1 

Bt/IJLDING 


BOILERS 


ENGINES 




CENEHAT0R3 


MOTOBS 


LIGHTING DATA 


KEATBWl DATA 


if 

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lOWEX & L1GM7IWG 


ELEVATORS 


COAL USED 


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4 


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4 

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1 


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fSO 


Z-fS 





31 


1SOO 


*•«<,' V *30400 


78 


'58,000 




m,ooopao 

































OPERATING DATA 357 

Current cost per annum, $26,113.35. 

26,113.35 

~-i =$0,019 per K.W.H. 

1,372.960 

Highest maximum demand for any month 340 K.W. 

Lowest maximum demand for any month 225 K.W. 

Average hours less than 100 K.W. demand 3,000 

Average hours between 100 and 220 K.W 2,400 

Average hours between 200 and 300 K.W 2,800 

Average hours between 300 and 400 K.W 560 

Under the above operating conditions the installation of two 200 K.W. 
and two 100 K.W. electric generating units would give the most flexible 
plant and allow ample reserve. 

Ample boiler capacity is now installed in the building, and it is be- 
lieved that better efficiency will be obtained during the summer months 
with the additional load required by the electric generating plant. 
Estimated cost of plant: 

Engines and generators S30,000 

Piping 2,500 

Switchboard changes 1,000 

Incidentals 500 

Total $34,000 a 

a The plant was installed for .$42,000. 

COAL 

To be safe and allow 50 pounds of steam per K.W.H. and a factor of 
evaporation of 8| pounds of water per pound of coal, we would have 6 
pounds of coal per K.W.H., and charging all coal used in six months of 
the year, and 20 per cent during six months of the seven that exhaust steam 
is utilized for heating: 

637,480 X 6 = 3,824,880 lbs. of coal 

735,480 X 6 X .2 = 882,576 lbs. of coal 

4,707,456 lbs. of coal = 2.100 tons. 
2,000 tons X 3.15 = $6,615.00. 

ASH REMOVAL 

Ash removal for 5645 tons of coal costs now $622.41. 
Ash removal for 2100 tons of coal will cost 8231.00. 

WATER 

Water used by the plant will be: 

4,707,456 pounds of coal X 8| = 39,228,800 pounds of water = 627,660 
cubic feet X 52.5 cents (per 1000 cubic feet) = $329.57 per annum. 



358 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 



LABOR 

Present cost With an electric generating plant 

1 chief engineer $2,200 . 00 1 chief engineer $2,200 . 00 

1 assistant chief engineer 1 ,800 . 00 1 assistant chief engineer 1 ,800 . 00 
3 assistant engineers. . . . 3,600.00 3 assistant engineers. . . . 3,600.00 

2 engineer helpers 2,000 . 00 4 engineer helpers 4,000 . 00 

3 oilers 2,520.00 4 oilers 3,360.00 

7 firemen 6,387.50 8 firemen 7,300.00 

3 firemen helpers .... 2,190.00 3 firemen helpers 2,190.00 

2 firemen helpers for 7 2 firemen helpers for 7 

months 852.00 months 852.00 



$21,549.50 $25,302.00 

OIL AND WASTE 

Estimated for electric generating plant $300.00 

REPAIRS 

$30,000 at H per cent $450.00 

INTEREST AND DEPRECIATION 

30,000 at 10 per cent $3,000.00 

Total cost to operate the proposed electric generating plant: 

Coal. $6,615.00 

Ashes 231 .00 

Water 329 . 57 

Labor 3,752.50 

Oil and waste 300.00 

Repairs 450.00 

Interest and depreciation 3,000.00 

Total annual cost $14,678.07 

Cost of current during present year $26,113.35 

Estimated cost of current with electric generating 

plant 14,678.07 

Estimated annual saving $11,435.28 

I recommend the installation of an electric generating plant in this 
building at an early date, as same will pay for itself in three years. 

Respectfully, 

The plant recommenced by the engineer was installed after a 
long controversy, and the writer takes pleasure in stating that after 
twelve months operation the annual saving to the Government by 



OPERATING DATA 359 

the installation of this plant has amounted to $15,984.78, and it is 
performing its work in a satisfactory manner. 

When a Federal building is erected in a city where a district 
heating company has steam or hot water mains in the vicinity, the 
heating apparatus is designed so that the building may be oper- 
ated either by its own boilers (which are always installed) or by 
the heating medium purchased from the district heating company. 
Upon receipt of the company's proposal for supply of the heating 
medium, which in the case of steam is nearly always based on a 
sliding scale so arranged that the price per thousand pounds de- 
creases as the amount used per month increases, it is necessary 
for the office to determine accurately whether it will be more 
economical to generate its own steam, or to purchase the steam 
from the company. The following method is used: 

The actual amount in square feet of direct radiation is taken off 
the plans, to which is added any fan blast surface and any gravity 
indirect surface. To reduce to equivalent direct radiation the 
amount of blast coil surface in square feet is multiplied by 3, and 
the gravity indirect is multiplied by 1J. The equivalent direct 
radiation is then assumed to condense during the 212 days of the 
average heating seasons 500 pounds of steam per square foot. 
To apply the sliding scale the total steam per season is apportioned 
as follows : 

October 1 to October 31 15 per cent of total 

November 1 to November 30. 15 per cent of total 

December 1 to December 31 20 per cent of total 

January 1 to January 31 25 per cent of total 

February 1 to February 28 15 per cent of total 

March 1 to March 31 15 per cent of total 

April 1 to April 30 5 per cent of total 

The total cost is thus ascertained if steam be purchased, and 
it is compared on the following basis with the cost of operating 
the boilers in the building: 

The total number of pounds of steam per annum as previously 
ascertained is divided by 7, which gives the number of pounds of 
coal per annum used under the boilers. This is reduced to tons 
and the local cost per ton of coal is applied. To the actual cost of 
coal is added the cost of ash removal, which is taken roughly as 
10 cents per ton of coal, and in the infrequent cases (especially in 



360 MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 

the smaller buildings) where labor can be saved by the purchase 
of steam the cost of the additional labor is added. The De- 
partment is usually willing to pay $100 or over per annum more 
for the purchase of steam in order to be relieved of the operation 
of the boilers, and secure freedom from smoke, dirt, etc. 

If hot water is the medium the same process is used, by reduc- 
ing the hot water radiation to a steam equivalent (dividing the 
hot water radiation by 1.6) to ascertain the amount of coal to be 
burned and compare it with the flat rate always quoted for hot 
water radiation by the local companies. 

South of the Mason and Dixon line the figure 500 above noted 
will become 450, while in San Francisco, Cal., it will approximate 
350 pounds per square foot direct steam radiation. 

The majority of the buildings are very small, and the mechanical 
equipment consists of a direct steam or hot-water heating appa- 
ratus and a gas and electric direct lighting system supplied with 
either gas or electricity from local companies. In these small 
buildings the matter of engineering personnel, purchase of sup- 
plies, fuel, etc., is merely routine. 

It was the practice of the Department to purchase coal on the 
B.t.u. basis for all buildings where the cost exceeded $1500 per 
annum, but this method of purchase has been discontinued except 
for the large buildings. 

When coal is purchased under the B.t.u. system the specifica- 
tions state what kind of coal is desired, and limit the amount of 
volatile matter and ash which will be permitted. 

Each bidder offers such coal as he thinks will meet the specifi- 
cation, and gives in his proposal the following information rela- 
tive to the coal he proposes to supply : 

Number of B.t.u. per pound of dry coal as received. 

Percentage of ash per pound of dry coal. 

Cost per ton of coal. 

As there is always a variation in the ash content of coal offered 
by the various bidders, it is necessary, in order to reduce all to 
the same basis, to fix a standard ash content and make an allow- 
ance for variation from same. 

The lowest ash content stated by any bidder is made the stand- 
ard, and all other coal is brought to this basis by adding 2 cents 



OPERATING DATA 361 

per ton to the price quoted for each 1 per cent or fraction thereof 
the ash content exceeds the arbitrary standard. 

When all proposals have been brought to the same basis in 
regard to ash content, the lowest price quoted per 1,000,000 
B.t.u. is readily ascertained by the following formula: 

~ , .,,. -p. , . 1,000,000 X price per ton of coal 

Cost per million B.t.u. = ' ' — =r- — - = — 7 r 

2240 X B.t.u. per pound 01 coal. 

When the coal purchased under the B.t.u. system is delivered 
at the building, samples are taken and sent to the Bureau of 
Mines for analysis, the result of which determines the payment to 
be made for the coal delivered. If the analysis shows that the 
contractor has fulfilled his agreement, no more and no less, the 
contract price is paid; otherwise, corrections above or below the 
contract price are made for variation in B.t.u. and ash. 

The correction for B.t.u. is made by the following formula: 

Delivered B.t.u. X contract price per ton . ., 

— - — — - — — r- = pnce paid per ton. 

Contract number 01 B.t.u. per pound 

For example: If the contractor stated that his coal contained 
14,000 B.t.u. per pound and the price per ton was $3, and the coal 
delivered contained 14,300 B.t.u. per pound, he would be paid 
per ton 

14,300X3 



14,000 



= S3. 0643 



The price to be paid must be further corrected for any varia- 
tion in ash content. For all coal, which by analysis contains less 
ash than that established in the proposal, a premium of 2 cents 
per ton for each whole per cent less ash is paid. An increase of 
2 per cent in ash over the contract amount is tolerated without 
deduction, but for any excess a penalty is exacted in accordance 
with the following table. 

When local conditions permit the choice of either gas or elec- 
tricity as the illuminating medium, preference is given to elec- 
tricity for many practical reasons, such as maintenance, adjust- 
ments, etc., and also on account of the great amount of heat 
generated by the gas, which is a decidedly objectionable feature 
during the summer months. 



362 



MECHANICAL EQUIPMENT OF FEDERAL BUILDINGS 





NO 


CENTS PER TON TO BE DEDUCTED 




ASH AS ESTAB- 
LISHED IN 


TION 
FOB 


2 


4 


7 


12 


18 


25 


35 


MAXIMUM 
LIMITS FOR 


PROPOSAL 














ASH 




BELOW 




Percentages of ash 


in dry coal 






per cent 




















5 


7 


7-8 


8-9 


9-10 


10-11 


11-12 


12-13 


13-14 


12 


6 


8 


8-9 


9-10 


10-11 


11-12 


12-13 


13-14 


14-15 


13 


7 


9 
10 
11 


9-10 
10-11 
11-12 


10-11 


11-12 


12-13 
13-14 
14-15 


13-14 


14-15 
15-16 
16-17 


15-16 
16-17 
17-18 


14 


8 


11-12 1 


14-15 
15-16 


14 


9 


12-13 


13-14 


15 


10 


12 
13 


12-13 
13-14 


13-14 
14-15 


14-15 
15-16 


15-16 


16-17 

17-18 


17-18 
18-19 




16 


11 


16-17 


16 


12 


14 


14r-15 


15-16 


16-17 


17-18 


18-19 


19-20 




17 


13 


15 


15-16 


16-17 


17-18 


18-19 


19-20 


20-21 




18 


14 


16 
17 


16-17 

17-18 


17-18 
18-19 


18-19 


19-20 
20-21 


20-21 
21-22 


21-22 




19 


15 


19-20 


19 


16 


18 


18-19 


19-20 


20-21 


21-22 


22-23 






20 


17 


19 


19-20 


20-21 


21-22 


22-23 








21 


18 


20 


20-21 


21-22 


22-23 










22 










With combination lighting fixtures designed to give satisfactory 
illumination using either tungsten lamps or Welsbach gas lamps, 
the cost of illuminating a building will be about the same for gas 
and electricicty if gas is selling at $1 per thousand cubic feet and 
electricity at 10 cents per kilowatt-hour. The theoretical ratio of 
cost based on equal illumination is approximately 30 to 1 on the 
basis that 1 watt of electricity will give 10 lumens on an average 
and gas 300 lumens per cubic foot on an average but actual ex- 
perience has demonstrated that the true ratio is i0 to 1 under 
practical operating conditions as found in Federal buildings. 

Where conditions permit the use of either gas or electricity 
their relative costs are carefully analyzed in each case, on the 
assumption that the full connected lighting load of a building 
will be in service 1200 hours per annum. The following data 
are used in connection with the gas lighting : 

Pilot uses T V cubic foot of gas per hour and burns continuously. 

Welsbach inverted No. 4 T uses 1.6 cubic feet per hourgives450 lumens. 
No. 3 T 2| cubic feet per hour gives 900 lumens. 

Junior upright about If cubic feet per hour give 350 lumens. Inverted 
No. 20 uses 9 cubic feet per hour gives 2400 lumens. Welsbach inverted 
No. 1 uses 3J-4 cubic feet per hour gives 400 lumens. Welsbach upright 
gallery burner uses 4| cubic feet per hour gives 800 lumens. 



APPENDIX 
GENERAL INSTRUCTIONS 

ISSUED TO DRAFTSMEN BY THE CHIEF MECHANICAL AND ELECTRICAL ENGI- 
NEER, OFFICE SUPERVISING ARCHITECT 

The first step taken in the design of the mechanical equipment of a Fed- 
eral building consists in acting on the survey which is secured by the office 
and forwarded to the Chief Mechanical and Electrical Engineer for check. 
As the proper design of the drainage system, gas, and water piping, and 
electrical service connections to buildings are dependent on a correct sur- 
vey, great care must be taken in acting on same, and the following are the 
principal items to be noted: 

Survey must give location of gas and water mains and sizes thereof. 
If no gas mains are shown, check survey and state in your note to engineer- 
in-charge "No gas mains shown." If water mains are not shown, return 
survey with request that size and location of water main be indicated. 
In event water or gas mains indicated on survey are smaller than 2-inch 
diameter (unless the gas is distributed at high pressure), return survey and 
request size and location of nearest large gas or water main. Many gas 
mains are now installed in which gas is under a pressure of several pounds 
and in consequence they are reduced greatly in size. 

See that location and sizes of sewers are given, and direction of flow and 
rate of fall. If an elevation is given on sewer without a specific state- 
ment as to what point it refers, request that this information be given, 
unless there is absolutely no question that sewer can drain a cellar 10 feet 
deep. 

In event sewer is shown but no elevation is given, request information 
relative to elevation of invert. 

If no sewer is available, and a cesspool or septic tank is not to be used, 
it will be necessary for the Government to build its o^n sewer, and you 
should call special attention to the matter in order that the necessary legal 
steps may be taken to secure right of way, exclusive jurisdiction, etc. 

Examine survey for electric light, power, telephone, telegraph and 
trolley poles, or for underground conduits; if all these points are covered 
satisfactorily, check survey. 

If no poles are indicated on survey and none appear in photographs, 
check survey. 

If the specific uses of the various poles shown are not noted, or if pho- 
tographs show poles adjacent to site which are not indicated on survey, 
request further information. 

363 



364 APPENDIX 

The second step in the preparation of the mechanical equipment draw- 
ings and specifications is the forwarding of data sheets to the custodian 
of the Government site and the action on same upon receipt of data sheets 
from him. 

These data sheets ask for information not covered by survey and proper 
answers to the questions propounded must be secured. 

Survey and data sheets must be compared to see that they agree and that 
data sheets are complete. If data sheet states that there are gas works in 
t.he city, and survey shows no gas mains, the custodian of site should be 
requested to state size and location of gas mains adjacent to site. 

When all the foregoing instructions have been attended to, the drafts- 
man will initial the data sheet and file it in the appropriate data book; 
and he will be held responsible for failure to secure at this time all neces- 
sary data. 

The next step in the design of the mechanical equipment is the com- 
pletion of preliminary drawings, which are tracings of the building plans, 
prepared by the architectural draftsman, showing arrangement of building. 

The mechanical draftsman will indicate on tracings: The entire plumb- 
ing and drainage system; all chases necessary for any part of mechanical 
equipment; the size and location of openings for smoke breeching and 
stack; size and location of all hot air flues and registers, cold air inlets, 
ventilators, vent ducts, flues and space required for boilers, fan, heaters, 
air washers, and other machinery that will be required in connection with 
heating and ventilating system; location of all outlets, cabinets, tablets 
and switchboard which will be required in connection with lighting; the 
space required for elevator machine, tank and pumps that may be required 
in connection with elevators; the space required for vacuum cleaner; and 
any other machinery that may be required in connection with mechanical 
equipment. When floor plans are at scale f inch to 1 foot, the mechanical 
draftsman will note on the preliminaries that architectural draftsman is 
not to indicate on his drawings any plumbing fixtures or piping but must 
indicate thereon all other items mentioned above and note also on drawings 
the finish of the toilet rooms. 

These preliminary tracings are returned to the architectural draftsman 
whose duty it is to arrange the building to receive the proposed mechanical 
equipment. 

This preliminary work fixes the design of the mechanical equipment with 
but little chance to change same later, and draftsmen must read carefully 
the following instructions before the preparation of the preliminaries. 

Consideration must be given to part of country in which building will be 
located; as to whether a district heating service is available; style of build- 
ing; uses to which various parts are to be put; appropriation available; and 
any other facts that will affect design of mechanical equipment. Consid- 
eration must also be given to the fact that the assignment of a building 
as indicated on preliminaries is likely to be changed before occupation, 
involving division of large rooms, conversion of storage spaces (where pro- 
vided with light) into offices, etc., and the mechanical equipment must be 



APPENDIX 365 

arranged as far as possible to accommodate such changes with a minimum 
amount of alteration and expense. 

In preparation of preliminaries the survey and data sheets must be 
consulted, and the layout must be made in pencil and approved by the 
Mechanical Engineer before any work is inked in. The general design of 
mechanical equipment for large buildings must be discussed with the 
Chief Mechanical and Electrical Engineer before laying out same. 

All vertical pipes in building must be concealed in chases, furring, look- 
outs, or closets, except when structural conditions prevent, and then pipes 
may be exposed in locations other than public lobby and court room. In 
addition to chases for plumbing pipes, indicate on preliminaries chases 
for heating risers of sufficient number to provide a chase for each riser, 
and a sufficient number of risers to require but one radiator on a floor 
to be connected to same riser. 

Heating pipes may be run in same chases with downspouts or vent pipes, 
but must not be in run in chases with soil or waste pipes unless absolutely 
necessary. No chase or piping to be run in vaults. 

Indicate also chases for electric conduits, which must never be run in 
same chases with heating or water pipes. Chases are not generally neces- 
sary for conduits where walls are furred, and need never be provided for 
distribution conduits except at cabinets. 

Between basement floor and under side of fireproofing of deepest first 
floor beam or girder there must be a clear height of not less than 8 feet 6 
inches; this is the minimum and must be exceeded when possible. 

Horizontal pipes may be exposed at ceilings of basement, toilet rooms, 
lookouts, mailing vestibule, workroom, and back of screen in money-order 
room provided screen extends to ceiling. In all other rooms pipe must be 
concealed in furring or floor construction. Toilet-rooms floors must not be 
raised above general floor level without special permission of Chief Me- 
chanical and Electrical Engineer. 

An Executive Order requires that hot water for cleaning purposes must 
be provided for all buildings. 

All buildings must be piped for gas even though there are no local 
gas works. This is a special departmental requirement. 

To ascertain for preliminary calculation the approximate amount of 
direct radiation required to heat the building, multiply the extreme out- 
side dimensions of building (length by width) by the distance from first 
floor to ceiling line of first, second, or third floor, as the case may be, to 
ascertain the cubic contents of heated space; then ascertain the gross wall 
area of the building, using extreme outside dimensions and the height as 
determined above; this amount divided by 4 is equal to the glass area and 
the gross wall area less glass equals amount of net wall area. The total 
B.t.u. necessary and the total radiation necessary can be determined 
quickly by multiplying the gross wall area as above obtained by 45 in ordi- 
nary climates and 50 in extreme cold climates to get B.t.u., and the result 
divided by 150 for water and 250 for steam will give the square feet of 
direct radiation necessary. Check this by building cubic contents heated 



366 APPENDIX 

by 100 for square feet if direct steam and by 60 for square feet if direct 
hot water. Also check by the rule that 1 square foot of direct steam ra- 
diation will be required for each square foot of glass in climates varying from 
— 10° to + 10° extreme temperature ; add 60 per cent to above for hot water. 

Ascertain from data sheets if a district steam or hot-water heating 
company is in operation or is contemplated in the city where building 
will be located. If such company exists ascertain the size of service pipe 
recommended by the heating company to supply the radiation required by 
the building. If steam is used, ascertain whether heating company will 
permit service pipe to grade towards street main. In such cases the heat- 
ing apparatus will be designed to be served from the district heating com- 
pany and the building will also be provided with boiler for breakdown 
service. 

Be sure that there are openings from outside of building to boiler room 
large enough to permit installation and future removal of boiler. The top 
of smoke flue or vent shaft must extend not less than 2 feet 6 inches above 
top of ridge of roof or level of parapet. 

When a masonry flue is used for smoke same must be provided with a 
terra-cotta lining. The largest terra-cotta lining available is 15| inches x 
15^ inches inside, and where a down-draft furnace is required, or where a 
larger stack is required, the masonry flue cannot be used. In this case 
return preliminaries to Mechanical Engineer calling attention to necessity 
for providing a vent shaft. Indicate size of opening for smoke breeching 
2 inches larger than round breeching or 2 inches larger each way than rec- 
tangular and give distance to center or bottom above floor. Note size of 
opening in vent shaft cover for smoke stack, which opening must be 4 
inches larger in diameter than the stack. 

To ascertain proper size of coal room for an average Federal building, 
ascertain the cubic contents based on extreme dimensions and height from 
bottom of basement to top of flat roof or average height of pitched roof, 
and figure that one pound of coal will be burned per season for each cubic 
foot of cubic contents and check on the basis of one-fourth pound of coal 
per square foot of radiation per day and with 200 days in heating season. 

Allow coal to be 6 feet deep in room and estimate 50 cubic feet of space 
per ton of coal. Generally figure to store entire season's supply in the small 
buildings. 

Light outlets are located on preliminaries to aid structural engineer to 
avoid same in designing framing, and also in order to prepare an estimate 
of cost of conduit and wiring system. Conditions must be carefully studied 
and light outlets definitely and correctly located. Where for lack of in- 
formation relative to construction certain light outlets cannot be definitely 
located, estimate the number of such outlets and include them in the esti- 
mate of cost. (For rules for calculating number of outlets see "Conduit 
and Wiring.") 

Estimate the number of tablets that will be required and determine if 
reasonably central locations can be obtained for same. If locations are 
difficult to find, or if tablets will be located on brick walls, obtain from ar- 



APPENDIX 367 

chitectural draftsman information relative to exact locations for tablets, 
and indicate on preliminary the chases as hereinbefore stated. 

In all buildings three stories or higher containing a court room, pro- 
vision must be made for an elevator. If appropriation will not warrant 
the installation of an elevator, a hoistway or stairwell large enough for a 
hoistway, and a room suitable for an elevator machine must be provided. 

A vacuum cleaning-system will not be installed in a building having a 
total floor area (including basement — of less than 50,000 square feet. When' 
a system is to be installed indicate space required for machinery and chases 
necessary for risers (see "Vacuum Cleaning"). 

Any special machinery or appliances such as pumps, tanks, etc., that 
may be necessary on account of local conditions, must be located on pre- 
liminaries in order that space may be reserved for same. 

In preparing preliminaries for extensions the report of the draftsman 
detailed to secure data must be carefully considered (having in mind also 
the amount of the appropriation available) in determining whether the 
entire mechanical equipment of the old building must be abandoned, or 
whether same shall be extended, to serve the addition. 

Consult Chief Mechanical and Electrical Engineer in regard to all ex- 
tensions, but before taking up the subject be in possession of all data, 
including amount of appropriation available per cubic foot of extension. 

The estimated value of the plumbing and drainage, plumbing marble, 
heating and ventilating apparatus, gas piping, conduit and wiring, clock 
system, telephone system, vault protection system, elevators, lighting fix- 
tures, etc., must be carefully determined, and noted on the preliminary 
drawings . The conduit and wiring system estimate placed on preliminaries 
is to include all special conduit systems. 

To ascertain the cost of the plumbing and drainage where the building is 
within 100 feet of city sewer to which it will connect, add together the 
number of water-closets, urinals, slop sinks, lavatories, shower baths, sinks, 
fire hose racks, and take four wall hydrants as one fixture and hot water 
boiler and heater as one fixture. Multiply the number of fixtures so ascer- 
tained by $125 for 80 fixtures and less, and by $115 for more than 80 fixtures. 

To ascertain cost of plumbing marble multiply the number of fixtures in 
toilet rooms by $75. If a terra-cotta private sewer must be run, estimate 
it at $1 per lineal foot if in earth and $3.50 if in rock ; and if brick or granite 
pavements must be replaced add $1 per lineal foot to above. Estimate 
$75 for each manhole; $200 for a cesspool, and $300 for a septic tank. For 
each water filter of 50 gallons capacity per minute (in new buildings) 
allow $600. Cost of gas piping system $3.50 per outlet. 

To estimate the cost of heating apparatus where direct radiation and a 
portable steel boiler with plain grate is used, multiply the number of square 
feet of radiation by $1.25 for steam and $1.10 for hot water if building is 
located in northern or eastern part of United States; and by $1.50 for 
steam and $1.35 for hot water if building is located in south or southwest. 
To this add $600 if down draft furnace is used. Brick-set, horizontal, 
return tubular boilers would not materially change the estimate. 



368 APPENDIX 

Add for cooling coil and connections for outside heating system 50 cents 
per square foot of indirect radiating surface. 

For automatic-temperature control add 60 cents per square foot of 
radiation. A fan system with air heated to 70° for ventilation only and 
with an air washer, will cost approximately $300 per 1000 cubic feet of air 
per minute for steam, plus 60 per cent for hot water for ventilating system 
only, exclusive of registers. 

Gravity-steam-indirect will cost $2 per square foot of radiation. 

Vacuum systems will cost approximately 50 cents per square foot of 
radiation in addition to cost of a standard one-pipe gravity-return appa- 
ratus. 

To estimate the cost of conduit and wiring system multiply the total 
number of ceiling outlets, bracket outlets, plug receptacles and post-office 
workroom floor outlets by $14 where building is located near a large city; 
by $16 when somewhat remote from a large city; and by $20 when in far 
west or south. For a check rule to ascertain the number of gas or electric 
outlets in a building, divide the total cubic contents by 2000. This result is 
outlets, not lights, as the number of lights will average 5 to the outlet. 

The cost of the lighting fixtures will be approximately $15 each and their 
aggregate cost, including installation, will be the same as that of the 
conduit and wiring system. 

Cost of conduit and wiring for the lighting system of an old fireproof 
uilding is $25 per outlet; wood construction $20 per outlet. 

Vault protection systems estimate at $20 per vault. 

Telephone systems $10 per outlet, for conduit and boxes; no wire or 
instruments. 

Clock system at $10 per outlet for conduit and boxes alone. 

Watchman's clock systems at $10 per outlet for conduit and boxes alone. 

Cost of clock system complete $35 for each secondary clock. 

Estimate for vacuum cleaning system : 

Six-sweeper plant $3,500 

Four-sweeper plant 3,000 

Three-sweeper plant 2,500 

Two-sweeper plant 2,000 

Each hydraulic lift operated by city water-pressure direct, estimate at 
$2000. This will include street connection. 

Hydraulic lift with pumping plant estimate at $3000. Push-bottom 
dumb-waiters (office standard) will cost $2000. Push button-freight ele- 
vator not exceeding 1200 pounds capacity $3000. 

For each standard drum-type electric passenger and freight elevator 
estimate $6000. For geared traction type the cost for each elevator will be 
about $7500. 

Very small hand-power lifts for machinery only, $150. 

Where shaft and enclosure are to be built for hand-power lift with car 
above 4 feet x 4 feet and capacity of 300 pounds, cost will average 



APPENDIX 369 

Based on the architectural cubic contents of a building, which is obtained 
by multiplying the extreme outside dimensions of building by the distance 
from basement floor to top of balustrade on a flat roof building or to mean 
height of roof on a steep pitched roof, the cost of the mechanical equipment 
will approximate the following figures when intelligent estimates are 
secured from contractors: 

Per cubic foot 

Plumbing and plumbing marble $0.02 

Direct heating 0125 

Conduit and wiring 0055 

The approximate cost of mechanical equipment based on total cost of 
our standard building is about : 

Per cent of total cost 
of building 

Plumbing and plumbing marble 6 

Direct heating 3^ 

Conduits and wiring 1| 

Gas piping 0.4 

Approximate cost of mecahnical equipment of a small one-story post- 
office building is roughly 12 per cent, and for a large building from 15 per 
cent to 20 per cent, of total cost of building (exclusive of land). 

The cost of our small standard buildings for entire completion including 
mechanical equipment is 35 cents per cubic foot. When the proposed 
building figures out below this, consult Chief Mechanical and Electrical 
Engineer. 

The cost of our standard extensions where some changes of magnitude 
occur in old part of building will average 45 to 50 cents per cubic foot of 
the extension only. When the figures are below this, consult Chief Me- 
chanical and Electrical Engineer. 

Attention is called to the fact that proposals based on architectural or 
mechanical drawings made on a scale of | inch to the foot, will average 10 
per cent higher than proposals based on same work on |-inch scale to the 
foot. 

The cost of the mechanical equipment of our standard one-story post- 
office buildings will average about as follows : 

Plumbing $2500 

Plumbing marble 900 

Heating apparatus 2500 

Conduit and wiring 900 

Gas piping 300 

For our standard three-story building it will average: 

Plumbing $4000 

Plumbing marble 1300 

Heating apparatus 4100 

Conduit and wiring 2300 

Gas piping .• 400 



370 APPENDIX 

The following data compiled by Mr. D. D. Kimball of New York, who 
has had a large experience in the mechanical equipment of similar public 
buildings will be ol interest and may be considered as authoritative. 

"Ina study of the cost of installation of heating and ventilating plants, 
made in a number of schools, it was found that the prevailing custom of 
apportioning a certain percentage of the total cost of the building for the 
heating and ventilating apparatus is of no value as these percentage ratios 
vary more than 100 per cent, even with similar classes of installations. 

For a given size building the cost of a heating and ventilating system 
will be approximately the same whether the building is a monumental 
stone structure or a plain wooden one, but the percentage of cost of the 
system will be very different. 

CLASSIFICATION OF SYSTEMS 

As a result of this study, the following scheme of classification has been 
arrived at : 

Class A. Plants providing for fire-tube boilers, double fan systems, air 
washers and humidifiers, individual or double duct systems and modulat- 
ing control of direct radiators and mixing dampers. 

Class B. Same as Class A, but using automatic stokers and water-tube 
boilers instead of fire-tube boilers. 

Class C. Same as Class A, but eliminating the modulation control of 
radiators and dampers and using the single trunk ducts. 

Class D. Same as Class C, except that it eliminates the use of air 
washers and humidification systems. 

Class E. All other systems. 

Manifestly there are many combinations of equipment which render an 
exact determination of classification difficult, but in general this classifi- 
cation has proven satisfactory. 

After a careful study of this method of classification and the figures on 
costs as thus obtained, it was found that the only satisfactory basis of 
determining the cost of the installation of the heating and ventilating 
plant was on the basis of the cubic feet of space in the building. The 
variation in costs within the different classes of systems is rarely over 10 
per cent from the average, the greatest variation occurring in Class A. 
The resulting costs are as follows : 

Class A, cost of plant per cubic foot 2.7 cents to 3.3 cents — average 
3.1 cents. 

Class B, cost of plant per cubic foot 3.3 cents to 3.8 cents — average 
3.4 cents. 

Class C, cost of plant per cubic foot 2.2 cents to 2.5 cents — average 
2.4 cents. 

Class D, cost of plant per cubic foot 2.2 cents to 2.3 cents — average 
2.25 cents. 

Class E, cost of plant per cubic foot 1.9 cents to 2.2 cents — average 
2.1 cents. 



APPENDIX 371 

If classes D and E were but abandoned and a proper amount of skill 
were used in the design, installation and operation of the remaining classes, 
a sufficient appropriation being provided for the installation and operation 
of the ventilating plant, it is believed that little basis would be left for 
complaint as to the success of the artificial ventilating system. 

Classes D and E are the result of a too limited appropriation, a demand 
for too large a building for the funds available, too much ornamentation, 
or too much equipment, or, in other words, an attempt to build a $100,000 
building with a $75,000" appropriation, the greatest sacrifice being made in 
connection with the heating and ventilating plant. Better were a proper 
building, well equipped, though smaller. 

As a matter of information it is interesting to note that the cost of 
plumbing equipment for school buildings ranges from three-quarters of a 
cent to one and one-half cents per cubic foot, the average being one and 
one-tenths cents. The cost of electrical equipment, exclusive of electric 
power plants, ranges from one-half to one cent per cubic foot, the average 
being seven-tenths per cubic foot. 

In the case of the heating and ventilating, plumbing and electrical work, 
the costs seem to be approximately the same in grade schools and high 
schools." 

Upon completion of preliminaries, prepare the insert specification for 
mechanical equipment if the mechanical equipment is to be let with the 
building, as is the case except in larger buildings where the cost of the 
entire mechanical equipment will approximate $25,000. 

The mechanical draftsman must follow up the job and at the proper time 
obtain of the architectural draftsman floor plans, and trace for finished 
heating and lighting if said floor plans are made I inch to the 1-foot scale; 
and for plumbing, heating and conduit and wiring if said floor plans are 
made | inch to the 1-foot scale. 

When an extension is to be made to an old building an engineering drafts- 
man is detailed to visit the building for the purpose of obtaining all data 
necessary as a basis for preparation of drawings and specifications for me- 
chanical equipment of the extension and for any required modifications, 
etc., in the apparatus in old portion of the building. 

A draftsman detailed for such duty must, before leaving the office, pro- 
vide himself with all necessary drawings of the old building, a set of draw- 
ings of the proposed extension, a B. and S. wire gauge, and a set of data 
sheets: familiarize himself with the proper use of transportation requests, 
with the keeping of an expense account, the preparation of vouchers, etc. ; 
and ascertain the amount appropriated for the extension, and the estimated 
cost of structural work of extension, and changes in old buildings. 

He must not discuss with the officials at the building the assignment, 
etc., of the proposed extension, nor permit anyone to examine the drawings 
for same; and must obtain and note data in accordance with the following 
general instructions : 

Conduit and wiring system. Indicate location of all light outlets, 
noting whether same are gas or electric or both, and ascertain the number of 



372 APPENDIX 

lights. Note the type of fixture, its condition, whether wired, and if pro- 
vided with finial or pendant switch. If new lighting fixtures are. neces- 
sary obtain all data necessary in order that specification for same may be 
prepared. 

Indicate swing of all doors of building. 

If electricity is used in old building for lighting, indicate location of 
snap switches, size of same, height above floor, and lights controlled by 
each switch. Give location of switch tablets or switchboards. Make 
diagram of same showing number, type, and size of switches and fuses. 
Also indicate whether slate or marble is used for panels and ascertain con- 
dition of same. Note especially if any spare switches are on panel boards 
and ascertain their size; also note location of wiring compartment on tab- 
lets and note construction of cabinets. If capacity of switch is not marked 
on same obtain dimensions of blades. 

Note manner in which wires are run, whether in conduit (iron or paper), 
in moulding, or on knobs or cleats, and condition of same. If possible, 
indicate runs of all circuits and groups of lights controlled by each switch 
on tablets. 

If possible give size of all circuits and in every case give size of main 
and subfeeders. Note whether feeders are two or three-wire. Where 
feeders are stranded measure outside diameter of copper cable and if 
possible give size of wire in strands and number of strands in ouside layer. 

Note floor construction, fire-proof, wood or otherwise, and whether fin- 
ished floors are wood, tile, or whatever construction. Give direction of 
run of floor boards in finished floors. 

Have superintendent or manager of lighting company fill in service 
data sheet, answering fully questions No. 15 and No. 17. Get answers to 
above questions also from telephone company. 

Make a sketch showing exact location on or distance from site of all 
poles (electric light and power, telephone or telegraph) . Indicate present 
services entering building and state whether overhead or underground, and 
give size. 

Heating and venlilation. Indicate on the drawings the location, size, 
construction and condition of all direct and indirect radiators in old build- 
ing, and size of connections, risers, and branches thereto. State whether 
radiator connections are above floor, in floor construction, or at ceiling 
below. Indicate location, size, and elevation above basement floor of all 
heating mains, and state type and the name of manufacturer of air valves 
and radiator valves in place. Indicate on drawings location, size, numbers, 
construction and condition of boiler or boilers; give grate area, water line, 
kind of coal burned, size and location of breeching and stack, and state 
whether or not the draft is good. State if building is satisfactorily heated 
and ventilated. If there is a ventilating system, show location and size 
of fans, motors, ducts, flues, registers, etc., and state condition; give ele- 
vation above basement floor of all parts of apparatus located near ceiling, 
and state if system is satisfactory or not. If there are no ventilators, 



APPENDIX 373 

report whether same are needed, especially in assembly rooms. State 
condition of atmosphere of the city, especially in regard to dust and soot. 

Plumbing and gas piping. Indicate on drawings the location of all 
plumbing fixtures and note type, name of manufacturer, and trade name 
(if obtainable) ; also their condition and whether they are satisfactory in 
number and operation. Give finish of all toilet rooms. Locate all down- 
spouts and all soil, waste, vent, and water risers of sanitary system. 

Indicate location and give size of all horizontal soil, waste, vent, water 
and gas piping. Give elevation above basement floor of all overhead 
piping. 

Indicate connection of building to city sewer and give size of connection 
and size of city sewer. Report whether drainage is satisfactory or if 
water backs up during rains. 

Give the distance from basement floor to center of horizontal soil pipes 
at summit, at point where same leave building, and at not less than two 
other points. Engage assistance (through custodian) to secure these data 
if necessary. 

Ascertain the condition of city water, to determine if filters are neces- 
sary, and the pressure carried. 

Fill out and return data sheets, with full report. 

Size of drawings. All tracings must be 24| inches x 37 inches, with 
f-inch margin; titles in capital letters designating branch of work, i.e., 
"Heating," "Electric Wiring," etc. 

Floor title to be placed midway between side borders, immediately 
below plan; scale in ^-inch letters immediately below floor title.' 

Title designating work to be placed midway between floor title and 
right-hand border line, about 2 inches above bottom border line. 

"Chief Mechanical and Electrical Engineer" in two lines to be in small 
italics, immediately above bottom border line, 6 inches from left hand 
border. 

Building title in right-hand bottom corner, and Supervising Architect's 
title in left-hand bottom corner, to be placed only on separate contract 
drawings. Space to be left for same otherwise. 

SUGGESTIONS TO SUPERINTENDENTS 

The following suggestions to Superintendents of Construction belonging 
to the office of the Supervising Architect, in relation to the mechanical 
equipment of Federal buildings, were incorporated in a paper presented at 
the annual meeting of the Treasury Construction Society in July, 1911, at 
St. Louis, Mo., and are included herein as being connected with the subject- 
matter of this book. 

The first precaution of the superintendent should be to familiarize him- 
self with the specification (not neglecting the general conditions) and the 
drawings governing the mechanical equipment, and to make marginal 
notes relative to any items which are not clear to him, or which appear to 



374 APPENDIX 

him to be in error, or, more important still, where there is a conflict between 
the drawings and the specification. If such matters are taken up with the 
office at that time for adjustment, for interpretation, or for whatever action 
is necessary, it will save a lot of trouble in the future. 

If a superintendent has had comparatively little experience with me- 
chanical equipment it is a good idea for him to confer with the foremen on 
the various branches of mechanical work as soon as they report at the 
building, frankly state that he is a little weak on those portions of the 
work, and warn them that while he may not see all the defects during the 
progress of the work the inspector of mechanical and electrical engineering 
will be very likely to when he comes along, and therefore that their own best 
interests will be served by strictly following the drawings and specifica- 
tions and using no material except that which has been specified and 
approved. 

Cases are bound to arise where structural conditions will prevent the 
installation of work or materials strictly in accordance with contract re- 
quirements, but it should be impressed upon the contractors' representa- 
tives at the building that they must not make any change, however slight, 
without the concurrence of the superintendent. The latter's authority 
permits him to direct a contractor to change the location of a pipe, a con- 
duit, a cabinet, and tablet, etc., where structural difficulties arise, pro- 
vided no change in 'price is involved, but the order to make the change must 
be made in writing, so that there may be no misunderstanding, and a 
duplicate of the letter should be placed on the superintendent's files for his 
own protection and for the information of the inspector who examines the 
installation. If the superintendent has any doubt as to his jurisdiction 
in the matter, or as to the best course to follow, it is well to refer the case 
to the office in advance of taking any action. 

Great care is taken by the office in selecting the materials and appliances 
to be used in the mechanical equipment, and the letter of approval gives 
name of manufacturer, trade name, and, where possible, catalogue number. 
After this formal approval, these materials and appliances are as much a 
part of the contract as anything that went before, and cannot be changed 
without permission of the Secretary of the Treasury, or an Assistant Sec- 
retary acting for him, and as all these changes cost the Department time 
and money they should be avoided whenever possible. If a superintendent 
recognizes the necessity of permitting a change to be made, i.e., where 
structural reasons demand it, where serious delay would result by insisting 
upon the use of exactly what has been approved, etc., etc., he should im- 
mediately obtain from the contractor a proposal to make the substitution, 
either with or without change in contract price, whichever the conditions 
warrant, and should forward it with a brief explanation and with his 
recommendation. If the conditions which make the change necessary or 
advisable were not anticipated (as may often be the case where extensions 
to old buildings are in progress), and an exigency exists, threatening de- 
lay to other work, or indicating the possibility of some complication, the 
superintendent should wire the office, stating briefly the conditions and 



APPENDIX 375 

that a proposal from the contractor has been or will be obtained and for- 
warded; and this wire should give the amount of money involved, exactly 
or approximately, if any change in price is contemplated, and state clearly 
just what material is to be changed and what they desire to use in place 
of it. 

Except under the above conditions the superintendent should see that 
the contractor uses what is specified and approved, and nothing else, and 
even though he is not very familiar with steam heating, plumbing, etc., 
he should not have much difficulty in identifying the approved devices and 
fixtures with the aid of the usual illustrations and descriptions. The con- 
tractors should be discouraged from asking for changes on the ground 
that they can get "something just as good" for less money, or that their 
sub-contractors have a large stock of some make on hand and prefer to use 
it, as these considerations have no weight with the Department, and the 
requests and refusals cumber the files unnecessarily and get in the way of 
more important business. 

Another very important precaution for the superintendent is to examine 
the mechanical equipment material as delivered, or as soon thereafter as 
other duties will permit, with a view to rejecting immediately any that is 
not in accordance with contract requirements. I have known cases where 
the office used several thousand words, and an enormous amount of time and 
patience, in obtaining the removal of inferior material, not acceptable 
even on the basis of a considerable deduction, which the contractor claimed 
had been put in with the concurrence of the superintendent, or, at least, 
without any objection from him, which was construed as being equiva- 
lent to permission to go ahead. These troubles, or many of them, would 
be avoided by a careful examination of material before installation. It 
is a fact that much of the trouble in making final settlements, so far as 
mechanical equipment is concerned, comes from unauthorized changes in 
appliances and materials, all of which have to be adjusted at that time. 

The new standard plumbing specifications adopted by the Treasury, 
War, and Navy Departments, are profusely illustrated and will tend to do 
away with all uncertainty in regard to the recognition of approved fixtures, 
etc., so far as new work is concerned. 

In connection with heating work superintendents will do well to provide 
themselves with the Crane Company's hand-book of their various steam 
specialties, and with the Ideal Fitter's hand-book, published by the Ameri- 
can Radiator Company, Chicago, 111. 

While the above-named firms generally decline to send their valuable 
catalogues to persons not engaged in the line of business to which they 
cater, they would undoubtedly be supplied to superintendents who wrote 
in their official capacity and stated that the books were for official use. 

Where omissions, additions, or changes are necessary in connection with 
work already under contract, and the superintendent is unable to get 
what he considers a reasonable figure, he should forward to the office 
without delay the best proposal he is able to obtain from the contractor, 
accompanied by a statement as to the necessity and the value (itemized) 



376 APPENDIX 

of the work, and a recommendation relative to the amount which should be 
fixed by the Department as compensation, It is not the intention to 
require contractors to perform additional work without a reasonable 
profit, and therefore superintendents should be liberal in estimating on 
same, giving due weight to the possibility of delaying other work under 
contract, to the distance from the market where the material must be 
obtained, and to the cost of expressage, freight, etc., adding a margin of 
not less than 25 per cent for profit, which includes the cost of doing busi- 
ness. With these features taken into account, and itemized in the 
superintendent's statement, the office will be very apt to follow his 
recommendations. 

In those cases where contractors are ordered to perform work at a fixed 
price, the superintendent should give it his particular attention, keep an 
accurate record of the labor and material used, and on completion report 
the facts to the office so that same may be available either to justify the 
position of the Department in case of controversy or to rectify any unin- 
tentional injustice done the contractor in fixing the price. 

Where it becomes necessary for the Department to order any portion of 
the work done at the contractor's expense, it is even more important for 
the superintendent to keep careful watch of the work as it progresses, to 
check up the materials and labor used, and to make sure that the contract 
requirements are strictly followed in every particular, as any failure in 
this direction would materially weaken the position of the Department 
in case of a controversy with the contractor in regard to the basis of 
settlement. 

If a superintendent after due effort is unable to obtain from a contrac- 
tor a reasonable proposal for work which is necessary, but is not closely 
associated with work under the contract, as, for instance, work in the old 
part of a building to which an extension is being added, or work in a new 
building which was not contemplated by the original contract and in no 
way affects it, as an independent gas or steam service connection, etc., the 
superintendent should forward such proposal as he is able to obtain from 
the contractor, accompanying same with an itemized statement of the 
necessity and value of the work, and with a proposal from some local 
contractor, or from sub-contractors on the job. 

In making estimates for partial payments on mechanical equipment the 
best results will be obtained by calling on the contractor for a detailed 
schedule of the values he assigns to the various portions of the work sat- 
isfactorily in place (no allowance being due for material delivered and 
not installed), and using these as a basis of comparison with the estimates 
made by the superintendent himself, who will thus be in a position to check 
up any errors in over-estimating or under-estimating on either side before 
the vouchers are prepared. 

The following data may be of service in this connection: 

On the heating work the boiler represents approximately 30 per cent of 
the cost of the job; radiation 20 per cent; piping 25 per cent; labor and 



APPENDIX 377 

profit 25 per cent; and when the boiler is set and all piping run, but radia- 
tion not connected, the job is "roughed in," and 50 per cent completed. 

The plumbing is considered 50 per cent completed, or "roughed in," 
when all pipes are in place and tested, but fixtures not set. The fixtures 
represent about 20 per cent of the value of the work, and the cost of installa- 
tion will average about $10 per fixture. 

The conduit and wiring system is 50 per cent completed, or "roughed 
in," when all conduits, steel cabinets, and outlet boxes are in place, but 
the marble tablets, wiring, etc., have not been installed. The marble 
tablets cost about 20 per cent of the job, and are worth about SI per cir- 
cuit to connect. In new buildings conduits of all sizes, in place, will 
average about $150 per 1000 feet. 

When a contract includes the removal of old material no credit should 
be given this factor under the head of percentages of completion on the 
semi-monthly reports, as this causes confusion in the office and has some- 
times resulted in sending an inspector to the building for a "preliminary 
inspection" before there was anything for him to see. 

Particular attention should be given by the superintendent to the pre- 
scribed tests of the mechanical equipment, which he should require the 
contractors to make in his presence at the proper time. The specifica- 
tions give full information relative to the kind of certificates required 
from contractor and superintendent, and it will help the mechanical inspec- 
tor a good deal if the superintendent will place a copy of such certificates 
on the building files. 

If any portions of the heating apparatus (such as risers in chases) are to 
be covered in by terra-cotta, etc., the superintendent should have such 
pipes tested in his presence with steam or water (water pressure not less 
than 50 pounds), and permit them to be covered if the results are satis- 
factory. No other portions of the heating installation are to have the 
non-conducting coverings applied until after the system has been inspected 
and tested by a mechanical inspector after completion, but the coverings 
should be at the building for his examination at the time of final inspection, 
and to insure this result the superintendent should promptly compare the 
delivered material with the approved samples of covering sent to him 
from the office, and require the contractors to correct any mistakes imme- 
diately. 

As indicated by the specifications, when lighting fixtures are under a 
separate contract, the connection of the lighting fixtures to the wiring 
system of the building should be deferred until after the latter has been 
tested out by an inspector of mechanical and electrical engineering, this 
having been found to be necessary on account of the controversies which 
used to arise between the wiring contractor and the fixture contractor when 
defects in the work developed and the responsibility lay between them. 

In order to be in a position to fix the responsibility for any defects 
which may develop during the fixture installation, the superintendent 
should be present when the fixture contractor makes the prescribed test of 



378 APPENDIX 

gas piping before beginning his work; and it is very important that the 
superintendent make sure that all gas nipples for lighting fixtures comply 
strictly with specification requirements, thus avoiding delays on this 
account after the installation is begun. 

Particular attention should be paid to tests of piping, wiring, etc., speci- 
fied to remain in place in buildings which are being extended, and if any 
parts are found to be not tight, or in any way unfit for use, a proposal for 
repairs or renewal, as the case demands, should be promptly forwarded 
by the superintendent, with his explanation and recommendation. 

Where the specification for extension of a building includes the removal 
of old mechanical equipment the superintendent should carefully note 
whether the contractor has the privilege of using any of the old material. 
Such material as the contractor has no right to use should be listed by the 
superintendent, divided into groups, such as steel and iron, copper, brass 
and lead, etc., giving the approximate weights, and proposals for purchase 
and removal should then be obtained and forwarded. The old-metal 
markets vary greatly, but the following prices are an indication of what the 
superintendent may expect under ordinary conditions: 

Wrought iron pipe $ 8 . 00 per ton 

Old boilers (whole) 4 . 00 per ton 

Iron castings and machinery 10 .00 per ton 

Copper wire, etc . 10 per pound 

Light brass castings 0.05 per pound 

Lead pipe . 03 per pound 

Old hose . 02 per pound 

Old plumbing fixtures No settled market price; 

variable, and generally very low. 

In regard to old material which is properly considered as debris, the 
superintendent should take whatever course will dispose of it with the 
least trouble and get it out of the way of building operations. 

It is the intention of the office to make at least two inspections of me- 
chanical equipment before the final inspection, and to make the first of these 
when the various branches are from 20 to 50 per cent completed, the exact 
time being regulated by the exigencies of the service, as there are many 
places to visit and but few inspectors to do the work. It is particularly 
important that the superintendents give their best attention to work that 
is to be covered before the inspectors' arrival, and allow no piping, etc., 
to be concealed until satisfactory tests have been made under the pre- 
scribed conditions. If a superintendent is in doubt as to whether certain 
work should be considered acceptable a call for an inspector will receive 
due consideration even before the usual time for making a preliminary 
examination. 

Probably all the superintendents know that the office requires formal 
notice from the contractor, by letter or telegram, when the mechanical 
equipment is ready for final inspection and test, this precaution being 
necessary in the event the inspection is delayed or repeated through some 



APPENDIX 379 

fault of the contractor, in which case the next visit of the inspector is at 
the contractor's expense. This notice should come through the superin- 
tendent when possible, with his confirmation of the contractor's statements 
relative to the stage of completion reached, or with such comments to the 
contrary as the conditions require. It will be helpful to those in charge of 
routing up the mechanical inspectors if the contractor's notice is obtained 
and forwarded a little in advance of actual completion, provided the con- 
ditions are such as to warrant contractor and superintendent in agreeing 
upon a definite date when everything will be ready for the inspector's 
examination. When the contractor is unwilling to bind himself to a defi- 
nite date in advance of actual completion, it will be helpful if the super- 
intendent will confer with the contractor and then give the office his best 
judgment relative to the probable date of readiness for the inspector. 
This will not involve the contractor, but will give the office a chance to 
route this job up with others in the vicinity if an inspector is going that way 
in the near future. The contractor's notice must follow at the proper 
time, of course, and a telegram from the superintendent stating that such 
notice is in his possession will be appreciated, and will frequently save an 
inspector a long trip back over a recently-traveled route. 

Some of the superintendents seem to misunderstand the status or the 
motives of the inspectors of mechanical and electrical engineering, and a 
word on that subject may not be amiss. 

The inspectors are the direct representatives of the Supervising Archi- 
tect, selected and appointed because their technical education, their ex- 
perience, and their judgment are needed in obtaining the execution of the 
mechanical and electrical branches in strict accordance with contract re- 
quirements. .In reporting every variation, however minor it may appear 
to be, they are simply carrying out their orders, and superintendents are 
not justified in believing that inspectors do this for the purpose of placing 
them before the Department in an unfavorable light. Judging from my 
own experience, the inspectors would be very glad if they did not find any- 
thing to criticise, and the office would certainly be overjoyed; and yet in 
cases where numerous and serious defects and omissions have been re- 
ported the superintendent in charge of the work has written the office in a 
strain indicating a spirit of hostility to the inspector, criticising him di- 
rectly and the office indirectly, and seeming to attribute the blame to every- 
body but the people at fault, i.e., the contractors and the superintendent. 
Inspectors differ, just like superintendents and other people, but the aver- 
age inspector if met in a fair spirit will be very glad to help the superin- 
tendent on the branches of work which are his special province, and to 
give him the benefit of his experience on such points as valuing work in 
place, estimating percentages of completion, interpreting drawings and 
specifications, etc.; and will consider these courtesies well repaid if the 
superintendent on his part will have all papers relating to mechanical 
equipment, beginning with the acceptance of proposal, carefulty filed in 
proper sequence and readily available for examination, for with these data, 
including the duplicates of test reports and copies of any orders the super- 



380 APPENDIX 

intendent has given for changes due to structural conditions, etc., as pre- 
viously referred to, the inspector will be saved much time and trouble 
and the office will reap a corresponding benefit in handling his report. 

About four years ago, for good reasons, the office discontinued the old 
practice of sending a copy of the mechanical inspector's report to the super- 
intendent with instructions to make necessary demands on the contrac- 
tors, and inaugurated the custom of making the demands directly on the 
contractors. Good results have been obtained, and the superintendents 
have doubtless been glad to be relieved of the clerical work involved in the 
former method. They should, however, follow the contractors up and 
hasten the completion of the work along the lines indicated by the de- 
mand letter, reporting to the office within a reasonable time if the action 
taken is not satisfactory. If any variations reported by the inspector 
are acceptable to the Department, either on a deduction basis or otherwise, 
the superintendent is notified so that he may govern himself accordingly, 
and the fact that certain items have been objected to by the inspector need 
not be taken into account by the superintendent (except when there is an 
obvious error of omission on the part of the office) unless the demand letter 
sustains the inspector's views. 

If a contractor fails to prosecute the mechanical work in harmony with 
the remainder of the building, or fails to supply omissions and correct 
defects in accordance with instructions of the superintendent or the office, 
as the case may be, the superintendent should after a reasonable time ad- 
dress a formal demand to the contractors, sending a copy of same to the 
office, with a brief explanation (unless the copy is self-explanatory) of the 
conditions which demand the action. If this does not promptly bring 
about the desired result it is no use for the superintendent to delay further, 
and he should report the case to the office for appropriate action. 

In the event a superintendent is transferred to another point of duty 
prior to the correction of defects reported at the time of final inspection 
of mechanical equipment, he should explain all items carefully to the cus- 
todian, and impress on him the necessity of submitting a detailed report 
as soon as conditions will warrant. Prompt action on this feature of the 
work will tend to expedite final settlement more than any other one thing, 
and help the office to avoid many of the criticisms now made on account 
of slow payments. 

Even when the structure and the mechanical equipment are included 
in one contract the office is frequently called upon to answer questions 
relative to the use of the heating apparatus during the erection of the build- 
ing. In these cases the building contractor may use the heating apparatus 
of the building, or any other medium which he desires, provided he furnishes 
temporary heat upon demand of the superintendent which is satisfactory 
to that officer. 

Where the heating apparatus is under a separate contract the matter of 
using it for temporary heat is for adjustment between the contractor and 
the building contractor, and the office is not interested in the basis of ad- 
justment. If the heating contractor does not want the apparatus used 



APPENDIX 381 

that is his privilege, and the building contractor must find some other 
means. 

In either of the above cases the superintendent should advise the con- 
tractor that the office will interpose no objection to the use of the heating 
apparatus for the purpose of furnishing temporary heat, provided it is 
presented for final inspection in a first-class condition, in full accordance 
with contract requirements. 

It sometimes occurs that a building is ready for general occupancy be- 
fore the heating apparatus is entirely completed, although the system is 
in such condition that it can be placed in service and operated by the cus- 
todian's force; and in such cases (as the interests of the Department will 
be served by the action) the superintendent should request the detail of an 
inspector of mechanical and electrical engineering, who will note all omis- 
sions and defects then existing, after which the system may be operated 
by the custodian's force on the understanding that the contractor will not 
be held responsible for any damage due to such operation, but must cor- 
rect all defects reported by the inspector and meet all responsibilities 
entailed by the " Guarantee" and "Notice to Surety" clauses of the 
specification. 

Where extensions are made to old buildings which are not vacated dur- 
ing building operations, special care is taken in preparing the specifications 
for mechanical equipment and certain portions of the general conditions 
under the construction specification, so that the building contractor is 
bound to insure proper heating of the occupied parts of the building and 
adequate lighting and toilet facilities, failing which the superintendent 
has the right to act at contractor's expense. When the superintendent's 
course in the matter is clearly set forth in the specification, which is the 
endeavor in all such cases, he should act promptly and discreetly and 
submit vouchers to the office for the necessary expense, with a letter of 
explanation. Before proceeding with any "exigency" work under these 
conditions, it is well for the superintendent to get at least two written pro- 
posals from local parties, and accept the one which is best for the interests 
of the Department, all things considered, forwarding both proposals to the 
office with the vouchers. 

Where the specifications are not clear in regard to the action to be taken 
by the superintendent in such cases, he should simply obtain and forward 
the bids with his explanation and recommendation and await instructions. 

It may be well to call attention to the fact that some cities require the 
"owner" to sign the application for a permit to open streets, connect to 
sewers, etc., and in those instances there is no objection to the superin- 
tendent signing the application as a matter of form, provided he accom- 
panies same with a statement that the signing in no way binds the Govern- 
ment or its agents to any payments therefor, as the specifications require 
the contractor to pay all necessary fees. 

At a convenient time it is also well to advise the city authorities that the 
local regulations in regardto plumbing, drainage, etc., do not apply within 
the Federal lot line, and therefore that the local inspectors have no juris- 
diction. 



382 APPENDIX 

While the specifications provide that gas and water pipe used in the 
work outside of the lot line are to be in accordance with the rules of the 
local companies so far as materials and method of laying are concerned, 
this does not apply to the building sewer; and the specifications do not 
permit any reduction in the size of the gas and water pipes. 

In all the matters treated of in this paper the office must rely to a great 
extent on the discretion, tact, and judgment of the superintendent, and 
perhaps it will help him in his work if he will remember that while he may 
be having a struggle with one building the office is having a struggle with a 
couple of hundred in various stages of completion. The amount of cor- 
respondence from all of them is enormous, and steadily increasing, and any- 
thing a superintendent does in the way of avoiding unnecessary additions 
to it is appreciated. He should not draw the office into a matter that is 
properly within his own jurisdiction, but if he must write on a subject, 
should make his communications as brief and explicit as possible. The 
ideal superintendent is the one who can erect a building in strict accordance 
with contract requirements, and with the minimum amount of controversy 
and correspondence, so that if it were not for his semi-monthly reports 
of progress the office could almost forget that such a building was under 
way. 



DIMENSIONS OF STANDARD U. S. TUBULAR BOILER FOR LOW PRESSURE HEATING WORK 



Diam . of boiler 

Length of tubes 

No. of 3£ " tubes 

No. of 4' tubes 

t to (! spacing (horiz.) 

ff to i of two center rows 

Top of top row of tubes above center line of boiler 

He ght of water line above center of boiler 

Height of water line above bottom of boiler 

Tube heating surface, sq. ft 

| of net heads, sq. ft 

J shell heating surface, sq. ft 

Total heating surface, sq. ft 

Thickness of shell 

Thickness o. f heads 

No. knee braces in rear head above tubes 

No. knee braces in front head above tubes 

No. knee braces in rear head below tubes 

. knee braces in front head below tubes 

No. 1{* thru braces below tubes 

m. safety valve for heating work 

Total tube area (internal sq. in.) 

m. return 

Diam. steam outlet 

., /8x B.H.S.— 48" to 60" diamA 
Radiation capacity (^ x B H s _ 6Q , diam op ) ■ ■ ■ 

Horse power of boiler ( ' ' — ' I 

Weight of plain boiler (approx.) 

of front, grates, castings and trimmings 

Total shipping wt. of boiler and trimmings 

Wt. of boiler full of water (item no. 27 + item no. 31) . 

Pounds water boiler holds when full 

, . , /inches 

S,ze phnn grate | sq {ee) . 

' beam columns (single setting) 

iron beams (single setting) 

1 beam columns (double setting) 8M8# 

' iron beams (double setting) 10"-15 # 

Lower grate (D.D. furnace) in 48 x 42 

Horse power (equipped with D.D. furnace) 



4J" 


4}' 


54' 


54" 


i'i" 


4}' 


9}' 


or 


33}' 


33|' 


286 


333 


13.5 


13.5 


75.36 


87.92 



5,775 
3,270 



S"-18* 
10"-15* 



4}' 
9}' 



3,370 
10,270 
17,300 
10,400 
48x54 

IS 
7 '-15* 
7"-9.75* 
8 "-18* 
10"-15* 
48x54 

70 



13.0 


13.0 


75.36 


87.92 


371 


430 


3%" 


A" 
4" 



40 

5,600 

3,170 

8,770 
13,650 

8,050 

48x42 

14 

7 "-15* 
7"-9.75* 

8 "-18* 
10"-15* 

48 x 42 



6,300 
3,270 
9,570 
15,710 
9,410 
48x48 

16 
7 "-15* 
7"-9.75* 
S'-18* 
10"-15* 
48x48 
45 



7,100 
3,370 
10,470 



18 
7 "-15* 
7"-9.75i 
8"-18* 
10"-15* 
48x54 



11J' 
38}" 



3,560 
10,510 
16,630 
9,680 
54x18 

18 
7 "-15* 
7"-9.75; 
9 "-21* 
12"-20.5. 
54x48 
70 



11}" 
3S|" 



11,280 
54x48 



7 "-15* 


7"-15* 


7"-9.75* 


7"-9.75« 


9 "-21* 


9 "-21* 


12"-20.5* 


12"-20.5* 


54x48 


54x54 


75 


90 



111' 

38}" 



16.1 
113.1 



9,000 
3,660 
12,660 
21,935 
12,935 
54x51 
20 



10,410 
16,710 



14J" 
4H- 



12 "-20. 5* 
54x48 



141" 
411" 



8,500 
3,660 
12,160 
21,685 
13,185 
54x54 

20 
7"-15* 
7"-9.75j 
9 "-21 * 
12"-20.5 
54x54 
75 



131" 
43i" 



9,400 
3,950 
13,350 
23,400 
14,000 
60x48 

20 
1 "-15* 
S"-11.25ii 
12'-31.5ii 
15 "-33* 
60x48 
95 



4J" 
54" 
72' 
13i" 
431" 



10,650 
4,010 
14,660 
26,650 
16,000 
00x54 

23 
7 "-15* 
8"-11.25jS 
12"-13.5* 
15 "-33* 
60x54 
100 



131" 
43J" 



19.92 
141.5 



90 

11,850 
4,160 
16,010 
29,800 
17,950 
60x60 

25 
7"-15* 
8*-ll.lS* 
12"-31.5jS 
15"-33* 
60x60 
115 



111' 
4H« 



HI* 



19.25 
125.7 



75 

9,500 
3,950 
13,450 
23,670 
14,170 
60x48 

20 
7 '-15* 
8"-11.25* 
12"-31.5* 



10,850 
4,010 
14,860 
27,170 
16,320 
60x54 

23 
7M5* 
8M1.25* 
12"-31.5jj 
15 "-33* 
60x54 
100 



Hi" 
414' 



12,000 
4,160 
16,160 
30,350 
18,350 
60x60 

25 
7*-15* 
8"-11.25* 
12 "-31. 5* 
15 '-33* 
60x60 
115 



44' 
64" 
61" 

ni' 

441" 
898 
24.0 
138.2 
1060 
S" 
i' 
16 
16 



19,280 
66x54 

25 
8"-18* 
9M3.25* 
12 "-40* 
15 "-40* 
66x54 
125 



66 

44' 
54" 
61" 

Hi 

44i* 
1010 
24.0 
155.6 
1189 

r 

4' 

16 
16 



110 

14,700 

5,130 

19,830 

36,390 

21,690 

66x60 

27.5 

8 '-18* 

9M3.25* 

12"-40* 

15 "-40* 

06x60 

140 



1009 

r 

4" 



33,377 

19,570 

06x54 
25 

8 MS* 
9"-13.25* 
12"-40* 
15"-40* 

66x54 
125 



46' 
951 
23.69 
156.5 
1132 

i" 
4" 

16 
16 



110 

15,000 

5,130 

20,130 

37,200 

22,200 

00x60 

27.5 

8"-18* 

9M3.25* 

12"-40* 

15 '-40* 

66x60 

140 



APPENDIX 



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CAPACITY OF CYLINDRICAL TANKS 



DIAMETER 


LENGTH 


WEIGHT 


CAPACITY 


inches 


feet 




gallons 




6 


434 


140 


24 


8 


543 


190 




10 


647 


235 




6 


558 


220 


30 


8 


690 


295 


10 


819 


365 




12 


933 


440 




6 


699 


315 




8 


872 


420 


36 


10 


1018 


525 




12 


1264 


630 




14 


1330 


735 




10 


1818 • 


720 


42 


12 


1960 


865 


14 


2200 


1000 




16 


2480 


1150 




12 


2310 


1130 




14 


2600 


1300 


48 


16 


2880 


1500 


18 


3170 


1700 




20 


3450 


1880 




24 


4030 


2260 




20 


5900 


2920 


60 


24 


6900 


3470 


30 


8300 


4400 




36 


9800 


5260 




20 


7400 


4240 


72 


24 


8500 


5090 


30 


10200 


6360 




36 


11900 


7630 




20 


9200 


5760 




24 


10500 


6910 


84 


30 


12400 


8645 




36 


14500 


10370 




40 


15800 


11522 


96 


36 


16400 


13500 



Weights given above are for bare tank and are based on following 



thickness. 

24 inches-36 inches diameter 

42 inches diameter 

48 inches diameter 

60 inches diameter 

72 inches-96 inches diameter 



y$ inch Shell 

1 inch Shell 

1 inch Shell 

ys inch Shell 

■A inch Shell 



| inch Heads 
ye inch Heads 

f inch Heads 
yw inch Heads 

h inch Heads 



384 



SPACE EEQUIRED FOR BRANCH CONNECTIONS 

MINIMUM HEIGHT OF CONNECTIONS OFF PIPE MAINS 

B= Vertical distance from center of main to center of branch if connec- 
tion is made on a 45° angle. 

C = Vertical distance from center of main to top of 45° elbow if con- 
nection is made on 45° angle. 

D = Vertical distance from center of main to center of branch if con- 
nection is made out of top of main. 

E = Vertical distance from center of main to top of elbow on branch if 
connection is made out top of main. 



MAINS 


BRANCHES 


B 


c 


D 


E 


BRANCHES 


MAINS 


inches 


inches 


inches 


inches 


inches 


inches 


inches 


inches 


2 


1 


91 

^8 


Q13 
"32 


Q31 
<J3T 


5 


1 


2 


2 


11 


2 s - 

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14 


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All 

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5| 


1 


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24 


11 


92 

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4! 
^8 


413. 
^16 


6A 


14 


2* 


24 


14 


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415. 
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54 


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5 


5 


2 


4-i 

^2 


6^ 


7ii 

1 32 


^32 


2 


5 


5 


24 


43 


«13 

"16 


731 
* 32 


10A 


24 


5 


6 


u 


43 

^8 


°8 


Ai5 
"16 


8t6 


14 


6 


6 


14 


45 

^8 


6 


7-5- 

' 16 


8j6 


14 


6 


6 


2 


AM. 

^32 


A21 
°32 


8 


944 


2 


6 


6 


^2 


"32 


7_9_ 
' 32 


8f 


10ft 


24 


6 


8 


2 


C27 
°32 


7II 

* 32 


9| 


10H 


2 


8 


8 


24 


6| 


8 A 


91 


1115 

J-J-ie 


24 


8 


8 


3 


61 


8f 


10* 


1913. 

J^-ie 


3 


8 



The above table prepared by Fred'k. D. B. Ingalls, M.E., indicates 
dimensions of branch connections when made up as close as possible with 
space nipple between tee on main and branch nipple. 

385 



CLIMATIC TEMPERATURES 

Lowest and Average Degrees in the U. S. 
(Compiled from U. S. Weather Bureau Records) 



State City Lowest *Av. 

Ala... Mobile - 1 57.7 

Montgomery .... — 5 56 . 1 

Ariz. .Flagstaff -17 34.8 

Phoenix 12 58.9 

Ark... Fort Smith -15 49.5 

Little Rock -12 52.0 

Cal... San Diego 32 57.2 

Independence... 10 48.7 

Col... Denver -29 38.4 

Grand Jet -16 39.2 

Conn. Hartford -14 36.3 

D. C. Washington -15 42.9 

Fla... Jupiter 24 69.8 

Jacksonville 10 60.9 

Ga ... Savannah 8 57.2 

Atlanta - 8 51.4 

IdahoBoise -28 39.6 

Lewiston — 18 42 .5 

111... .Chicago -23 35.9 

Springfield -22 39.0 

Ind . . Indianapolis — 25 40 . 4 

Evansville — 15 44.1 

la. ...Sioux City -3 32.1 

Keokuk -24 37.6 

Kan. .Ft. Dodge -26 .... 

Wichita -22 42.9 

Ky... Louisville -20 45.0 

La.... New Orleans 7 60.5 

Shreveport — 5 55 .7 

Mc.Eastport -21 31.1 

Portland -17 33.5 

Md. . .Baltimore - 7 43 .3 

Mass. Boston -13 37.2 

Mich. Alpena -27 29.1 

Detroit -24 35.3 

Minn.Duluth -41 25.5 

Minneapolis - 33 28 . 4 

Miss.. Meridian -6 53.9 

Vicksburg — 1 56.0 

Mo. ..Springfield -29 43.0 

Hannibal -20 39.7 

Mont. Havre -55 27.7 

Helena -42 30.9 



State City Lowest *Av. 

Neb.. North Platte. ...-35 34.6 

Lincoln -26 35.8 

Nev.. Carson City -22 . .. 

Winnemucca —28 37.9 

N.H.Concord 33.1 

N. J.Atlantic City....- 7 41.6 

N. Y.Binghamton -26 34.1 

New York City..- 6 40.1 

N. M.Roswell -18 48.9 

Santa Fe -13 38. C 

N.C.Hatteras...... .. 8 53.3 

Charlotte -5 49.8 

N. D.Devil's Lake -51 18.9 

Bismarck —44 23.5 

Ohio. .Toledo -16 36.8 

Columbus -20 39.8 

Okla.. Oklahoma -17 47.1 

Ore.. .Baker City -20 34.1 

Portland - 2 45.4 

Pa. . .Pittsburg -20 40.8 

Philadelphia -6 41.8 

R. I.Providence -12 37.5 

Block Island....- 4 39.7 

S. C.Charleston 7 56.9 

Columbia - 2 53.5 

S. D.Huron -43 25.9 

Yankton -32 31.2 

Tenn.Knoxville -16 47.0 

Memphis -9 50.7 

Tex... Corpus Christi. . 11 62.7 

Fort Worth - 8 49.5 

Utah . Salt Lake City . . - 20 39 . 7 

Vt....Northfield -32 27.8 

Va. ..Cape Henry 5 48.6 

Lynchburg ......— 6 45 . 2 

Wash. Seattle 12 44.3 

Spokane -30 37.0 

W.Va.Parkersburg -27 41 .9 

Elkins -21 38.8 

Wis. .La Crosse.. -43 31.2 

Milwaukee -25 32.4 

Wyo.. Cheyenne -38 33.7 

Landor -36 29.0 



* October 1st to May 1st. All stated in Fahrenheit. 

386 



TABLE OF THE PROPERTIES OF SATURATED STEAM 

FROM PEABODY'S TABLES 







TOTAL 












GAUGE 

PRESSURE IN 

LBS. PER SQ. 

INCH 


TEMPERA- 
TURE IN 
DEGREES 
F. 


HEAT IN 
HEAT 
UNITS 
FROM 
WATER AT 
32° F 


HEAT 
UNITS IN 
LIQUID 
FROM 
32° F. 


HEAT OF 
VAPORIZA- 
TION IN 
HEAT 

UNITS 


DENSITY 

OF 

WEIGHT 

OF 1 CU. 

FT. IN LBS. 


VOLUME 

OF 1 LB. 

IN CUBIC 

FEET 


WEIGHT 

OF 1 CU. 

FOOT OF 

WATER 





212.00 


1146.6 


180.8 


965.8 


0.03760 


26.60 


59.76 
59.64 


10 


239.36 


1154.9 


208.4 


946.5 


0.06128 


16.32 


59.04 


20 


258.68 


1160.8 


227.9 


932.9 


0.08439 


11.85 


58.50 


30 


273.87 


1165.5 


243.2 


922.3 


. 1070 


9.347 


58.07 


40 


286.54 


1169.3 


255.9 


913.4 


. 1292 


7.736 


57.69 


50 


297.46 


1172.6 


266.9 


905.7 


0.1512 


6.612 


57.32 


55 


302.42 


1174.2 


271.9 


902.3 


0.1621 


6.169 


57.22 


60 


307 . 10 


1175.6 


276.6 


899.0 


. 1729 


5.784 


57.08 


65 


311.54 


1176.9 


281.1 


895.8 


. 1837 


5.443 


56.95 


70 


315.77 


1178.2 


285.6 


892.7 


. 1945 


5.142 


56.82 


75 


319.80 


1179.5 


289.8 


889.8 


0.2052 


4.873 


56.69 


80 


323.66 


1180.6 


293.8 


886.9 


0.2159 


4.633 


56.59 


85 


327.36 


1181.8 


297.7 


884.2 


0.2265 


4.415 


56.47 


90 


330.92 


1182.8 


301.5 


881.5 


0.2371 


4.218 


56.36 


95 


334.35 


1183.9 


305.0 


879.0 


0.2477 


4.037 


56.25 


100 


337.66 


1184.9 


308.5 


876.5 


0.2583 


3.872 


56.18 


105 


340.86 


1185.9 


311.8 


874.1 


0.2689 


3.720 


56.07 


110 


343.95 


1186.8 


315.0 


871.8 


0.2794 


3.580 


55.97 


115 


346.94 


1187.7 


318.2 


869.6 


0.2898 


3.452 


55.87 


120 


349.85 


1188.6 


321.2 


867.4 


0.3003 


3.330 


55.77 


125 


352.68 


1189.5 


324.2 


865.3 


0.3107 


3.219 


55.69 


130 


355.43 


1190.3 


327.0 


863.3 


0.3212 


3.113 


55.58 


135 


358 . 10 


1191.1 


329.8 


861.3 


0.3315 


3.017 


55.52 


140 


360.70 


1191.9 


332.5 


859.4 


0.3420 


2.924 


55.44 


145 


363.25 


1192.8 


335.2 


857.5 


0.3524 


2.838 


55.36 


150 


365.73 


1193.5 


337.8 


855.7 


0.3629 


2.756 


55.29 


155 


368.62 


1194.3 


340.3 


853.9 


0.3731 


2.681 


55.22 


160 


370.51 


1195.0 


342.8 


852.1 


0.3835 


2.608 


55.15 


165 


372.83 


1195.7 


345.2 


850.4 


0.3939 


2.539 


55.07 


170 


375.09 


1196.3 


347.6 


848.7 


0.4043 


2.474 


54.99 


175 


377.31 


1197.0 


349.9 


847.1 


0.4147 


2.412 


54.93 


180 


379.48 


1197.7 


352.2 


845.4 


0.4251 


2.353 


54.86 


185 


381.60 


1198.3 


354.4 


843.9 


0.4353 


2.297 


54.79 


190 


383.70 


1199.0 


356.6 


842.3 


0.4455 


2.244 


54.73 


195 


385.75 


1199.6 


358.8 


840.8 


0.4559 


2.193 


54.66 


200 


387.76 


1200.2 


360.9 


839.2 


0.4663 


2.145 


54.60 


205 


397.36 


1203 . 1 


370.9 


832.2 


0.5179 


1.930 


54.27 


250 


406.07 


1205.8 


380.1 


825.7 


0.5699 


1.755 


54.03 


275 


414.22 


1208.3 


388.5 


819.8 


0.621 


1.609 


53.77 


300 


421.83 


1210.6 


396.5 


814.1 


0.674 


1.483 


53.54 



387 



388 



APPENDIX 



EXPANSION TANKS 



SIZE 


CAPACITY 


SQUAEE FEET 
OP BADIATION 


inches 


gallons 




10 x20 


8 


250 


12 x20 


10 


300 


12x30 


15 


500 


14x30 


20 


700 


16x30 


26 


950 


16x36 


32 


1300 


16x48 


42 


2000 


18x60 


66 


3000 


20x60 


82 


5000 


22x60 


100 


6000 



TABLE GIVING VELOCITY OF FLOW OF WATER IN FEET PER 
MINUTE, THROUGH PIPES OF VARIOUS SIZES, FOR VARYING 
QUANTITIES OF FLOW 



« 

h 

§! 

►J S 
^ S 


| INCH 


1 INCH 


1| INCH 


1| INCH 


2 INCH 


2| INCH 


3 INCH 


4 INCH 


5 


218 


122| 


78| 


54* 


30| 


19| 


13| 


7f 


10 


436 


245 


157 


109 


61 


38 


27 


15| 


15 


653 


367^ 


235* 


163| 


914 


58| 


40| 


23 


20 


872 


490 


314 


218 


122 


78 


54 


30f 


25 


1090 


612| 


392* 


272i 


152| 


97* 


67i 


38* 


30 




735 


451 


327 


183 


117 


81 


46 


35 




857* 


549| 


381* 


213* 


146| 


941 


53f 


40 




980 


628 


463 


244 


156 


108 


61* 


45 




11021 


706| 


490| 


274* 


1751 


1211 


69 


50 








785 


545 


305 


195 


135 


76| 


75 










1177| 


817| 


457| 


292| 


2021 


115 


100 












1090 


610 


380 


270 


153| 


125 














762* 


487i 


337i 


191| 


150 














915 


585 


405 


230 


175 














1067* 


682| 


472i 


268| 


200 














1220 


780 


540 


306f 



APPENDIX 



389 



SPECIFIC HEAT OF BODIES 



Specific 
Material Heat 

Cast Iron 0.12983 

Wrought Iron... 0.11379 

Lime 0.09555 

Copper.: 0.09515 

Brass 0.09391 

Silver 0.05701 

Tin 0.05695 

Mercury 0.03332 



Specific 
Material Heat 

Gold 0.03244 

Platina 0.03243 

Lead 0.03140 

Bismuth 0.03084 

Nickel '. .. 0.10860 

Ice 0.50400 

Coal 0.27770 

Coke 0.20085 



Material 

Glass 

Burnt Clay. . . 
Brickwood. . . . 
Water at 32°.. 
Alcohol (S. G. 

793) 

Petroleum. . . . 

Olive Oil 

Air 



Specific 
Heat 

0.19768 
0.18500 
0.20000 
1.00000 

0.62200 
0.43400 
0.30960 
0.23700 



TABLE GIVING LOSS IN PRESSURE DUE TO FRICTION IN 
POUNDS, PER SQUARE INCH, FOR PIPE 100 FEET LONG 

BY G. A. ELLIS, C.E. 



Q 

a 

o 

03 
< 


















« f 


f INCH 


1 INCH 


lj INCH 


\\ INCH 


2 INCH 


2| INCH 


3 INCH 


4 INCH 


° a 

c 


















5 


3.3 


0.84 


0.31 


0.12 










10 


13.0 


3.16 


1.05 


0.47 


0.12 










15 


28.7 


6.98 


2.38 


0.97 












20 


50.4 


12.3 


4.07 


1.66 


0.42 










25 


78.0 


19.0 


6.40 


2.62 




0.21 


0.10 






30 




27.5 


9.15 


3.75 


0.91 










35 




37.0 


12.4 


5.05 












40 




48.0 


16.1 


6.52 


1.60 










45 








20.2 


8.15 












50 










24.9 


10.0 


2.44 


0.81 


0.35 





09 


75 










56.1 


22.4 


5.32 


1.80 


0.74 






100 












3.90 


9.46 


3.20 


1.31 





33 


125 














14.9 


4.89 


1.99 






150 














21.2 


7.0 


2.85 





69 


175 














28.1 


9.46 


3.85 






200 














37.5 


12.47 


5.02 


1 


22 



390 



APPENDIX 



HORSE-POWER OF A LEATHER BELT ONE INCH WIDE 



VELOCITY 




LACED BELTS 


— TH.CKNESS IN INCHES 




IN FEET PER 
SECOND 


i 

7 143 


i 
6 

.167 


3 
16 

.187 


3 2 

.219 


i 

*250 


5 
16 

.312 


i 

.333 


10 


.51 


.59 


.63 


.73 


.84 


1 05 


1.18 


15 


.75 


.88 


1.00 


1.16 


1.32 


1.66 


1.77 


20 


1.00 


1.17 


1.32 


1.54 


1.75 


2.19 


2.34 


25 


1.23 


1.43 


1.61 


1.88 


2.16 


2.69 


2.86 


30 


1.47 


1.72 


1.93 


2.25 


2.58 


3.22 


2.44 


35 


1.69 


1.97 


2.22 


2.59 


2.96 


3.70 


3.94 


40 


1.90 


2.22 


2.49 


2.90 


3.32 


4.15 


4.44 


45 


2.09 


2.45 


2.75 


3.21 


3.67 


4.58 


4.89 


50 


2.27 


2.65 


2.98 


3.48 


3.98 


4.97 


5.30 


55 


2.44 


2.84 


3.19 


3.72 


4.26 


5.32 


5.69 


60 


2.58 


3.01 


3.38 


3.95 


4.51 


5.64 


6.02 


65 


2.71 


3.16 


3.55 


4.14 


4.74 


5.92 


6.32 


70 


2.81 


3.27 


3.68 


4.29 


4.91 


6.14 


6.54 


75 


2.89 


3.37 


3.79 


4.42 


5.05 


6.31 


6.73 


80 


2 94 


3.43 


3.86 


4.50 


5.15 


6.44 


6.86 


85 


2.97 


3.47 


3.90 


4.55 


5.20 


6.50 


6.93 


90 


2.97 


3.47 


3.90 


4.55 


5.20 


6.50 


6.93 






APPENDIX 



191 



REFRIGERATION DATA 



The following tables give the transmission per lineal foot of pipe in 
B. t. u. per 24 hours per degree difference between water and air for the 
best moulded cork covering. 



PIPE SIZE 
INCHES 


ICE "WATER 


STANDARD 
BRINE 


SPECIAL 
BRINE 


BARE PIPE 


1 
2 


3.84 


3.37 


2.92 


9.50 


3 

4 


4.00 


3.53 


3.17 


11.88 


1 


4.26 


3.73 


3.22 


14.81 


H 


4.78 


3.87 


3.43 


18.77 


H 


5.27 


3.96 


3.67 


21.49 


2 


5.88 


4.44 


3.90 


26.80 


2* 


6.98 


4.84 


4.40 


32.46 


3 


7.30 


5.20 


4.83 


39.58 


3^ 


7.82 


5.46 


4.78 


45.24 


4 


8.29 


6.21 


5.31 


50.89 


^2 


9.20 


5.93 


5.02 


56.55 


5 


9.84 


6.75 


5.61 


62.88 


6 


10.49 


7.03 


5.98 


74.87 


7 


12.05 


8.49 


6.54 


86.18 


8 


11.41 


8.72 


7.10 


97.49 


9 


14.62 


9.04 


7.67 


108.80 


10 


14.79 


10.01 


8.30 


121.56 


12 


19.98 


11.46 


9.43 


144.20 


14 


21.71 


12.36 


10.13 


158.34 


16 


24.50 


13.80 


11.26 


180.96 



The "Ice Water" covering varies from 1\ inches to 2 inches thick for 
the various sizes. 

The "Standard Brine" varies from If inches to 3 inches thick for the 
various sizes. 

The "Special Brine" varies from 2f inches bo 4 inches thick for the 
various sizes. 

Above data from Armstrong Cork Co. 



392 



APPENDIX 



PRESSURE IN INCHES OF WATER 

And corresponding pressure in ounces, with velocities of air due to pressures 



PRESSURE 

PER SQUARE 

INCH IN 

INCHES OF 

WATER 


CORRESPONDING 

PRESSURE 

IN OUNCES PER 

SQUARE INCH 


VELOCITY DUE 

TO THE 

PRESSURE IN 

FEET PER 

MINUTE 


PRESSURE PER 

SQUARE INCH 

IN INCHES 

OF WATER 


CORRESPONDING 

PRESSURE 

IN OUNCES PER 

SQUARE INCH 


VELOCITY DUE 

TO THE 

PRESSURE IN 

FEET PER 

MINUTE 


1 
32 


.01817 


696.78 


5 
8 


.36340 


3,118.38 


1 
16 


.03634 . 


987.66 


3 

4 


.43608 


3,416.64 


1 
8" 


.07268 


1,393.75 


7 
8 


.50870 


3,690.62 


3 
16 


. 10902 


1,707.00 


1 


.58140 


3,946.17 


1 
4 


. 14536 


1,971.30 


l* 


.7267 


4,362.62 


5 
16 


.18170 


2,204.16 


H 


.8721 


4,836.06 


3 

8 


.21804 


2,414.70 


J-4 


1.0174 


5,224.98 


1 
2 


.29072 


2,788.74 


2 


1 . 1628 


5,587.58 






PRESSURE IN OUNCES PER SQUARE INCH 

With velocities of air due to pressures 



PRESSURE 

IN OUNCES 

PER 

SQUARE 

INCH 


VELOCITY 
DUE TO 

THE PRES- 
SURE IN 

FEET PER 
MINUTE 


PRESSURE 

IN OUNCES 

PER 

SQUARE 

INCH 


VELOCITY 

DUE TO 
THE PRES- 
SURE IN 

FEET PER 
MINUTE 


PRESSURE 

IN OUNCES 

PER 

SQUARE 

INCH 


VELOCITY 

DUE TO 
THE PRES- 
SURE IN 
FEET PER 
MINUTE 


PRESSURE 

IN OUNCES 

. PER 

SQUARE 

INCH 


VELOCITY 

DUE TO 
THE PRES- 
SURE IN 
FEET PER 
MINUTE 


.25 


2,582 


2.25 


7,787 


5.50 


12,259 


11.00 


17,534 


.50 


3,658 


2.50 


8,213 


6.00 


12,817 


12.00 


18,350 


.75 


4,482 


2.75 


8,618 


6.50 


13,354 


14.00 


19,138 


1.00 


5,178 


3.00 


9,006 


7.00 


13,873 


14.00 


19,901 


1.25 


5,792 


3.50 


9,739 


7.50 


14,374 


15.00 


20,641 


1.50 


6,349 


4.00 


10,421 


8.00 


14,861 


16.00 


21,360 


1.75 


6,861 


4.50 


11,065 


9.00 


15,795 






2.00 


7,338 


5.00 


11,676 


10.00 


16,684 







APPENDIX 



393 



WEIGHTS OF STEEL 



NO. OF 

GAUGE 


APPROXIMATE THICK- 
NESS IN FRACTIONS 
OF AN INCH U. S. 
STANDARD 


APPROXIMATE THICK- 
NESS IN DECIMAL 
PARTS OF AN INCH 
U. S. STANDARD 


WEIGHT PER SQUARE 
FOOT I N POUNDS 
AVOIRDUPOIS IRON 


WEIGHT PER SQUARE 
FOOT IN POUNDS 
AVOIRDUPOIS STEEL 


S 
< 

n 

o 

"A 

s 

£ 

S 


BROWN & 
SHARPE 


BRITISH 
IMPERIAL 


NO. OF 

GAUGE 


0000000 


1-2 


.5 


20.00 


20.4 






.500 


70 


000000 


15-32 


.46875 


18.75 


19.125 






.464 


6« 


00000 


7-16 


.4375 


17.50 


17.85 






.432 


5o 


0000 


13-32 


.40625 


16.25 


16.575 


.454 


.46 


.400 


40 


000 


3-8 


.375 


15. 


15.30 


.425 


.40964 


.372 


30 


00 


11-32 


.34375 


13.75 


14.025 


.380 


.3648 


.348 


20 





5-16 


.3125 


12.50 


12.75 


.340 


.32486 


.324 





1 


9-32 


.28125 


11.25 


11.475 


.300 


.2893 


.300 


1 


2 


17-64 


.265625 


10.625 


10.8375 


.284 


.25763 


.276 


2 


3 


1-4 


.25 


10. 


10.2 


.259 


.22942 


.252 


3 


4 


15-64 


.234375 


9.375 


9.5625 


.238 


.20431 


.232 


4 


5 


7-32 


.21875 


8.75 


8.925 


.220 


.18194 


.212 


5 


6 


13-64 


.203125 


8.125 


8.2875 


.203 


. 16202 


.192 


6 


7 


3-16 


.1875 


7.5 


7.65 


.180 


. 14428 


.176 


7 


8 


11-64 


.171875 


6.875 


7.0125 


.165 


.12849 


.160 


8 


9 


5-32 


.15625 


6.25 


6.375 


.148 


.11443 


.144 


9 


10 


9-64 


. 140625 


5.625 


5.7375 


.134 


.10189 


.128 


10 


11 


1-8 


.125 


5. 


5.1 


.120 


.090742 


.116 


11 


12 


7-64 


.109375 


4.375 


4.4625 


.109 


.080808 


.104 


12 


13 


3-32 


.09375 


3.75 


3.825 


.095 


.071961 


.092 


13 


14 


5-64 


.078125 


3.125 


3.1875 


.083 


.064084 


.080 


14 


15 


9-128 


.0703125 


2.8125 


2.86875 


.072 


.057068 


.072 


15 


16 


1-16 


.0625 


2.5 


2.55 


.065 


.05082 


.064 


16 


17 


9-160 


.05625 


2.25 


2.295 


.058 


.045257 


.056 


17 


18 


1-20 


.05 


2. 


2.04 


.049 


.040303 


.048 


18 


19 


7-160 


.04375 


1.75 


1.785 


.042 


. 03589 


.040 


19 


20 


3-80 


.0375 


1.50 


1.53 


.035 


.031961 


.036 


20 


21 


11-320 


. 034375 


1.375 


1.4025 


.032 


.028462 


.032 


21 


22 


1-32 


.03125 


1.25 


1.275 


.028 


.025347 


.028 


22 


23 


9-320 


.028125 


1.125 


1.1475 


.025 


.022571 


.024 


23 


24 


1-40 


.025 


1. 


1.02 


.022 


.0201 


.022 


24 


25 


7-320 


.021875 


.875 


.8925 


.020 


.0179 


.020 


25 


26 


3-160 


.01875 


.75 


.765 


.018 


.01594 


.018 


26 


27 


11-640 


.0171875 


.6875 


.70125 


.016 


.014195 


.0164 


27 


28 


1-64 


.15625 


.625 


.6375 


.014 


.012641 


.0148 


28 


29 


9-640 


.0140625 


.5625 


.57375 


.013 


.011257 


.0136 


29 


30 


1-80 


.0125 


.5 


.51 


.012 


.010025 


.0124 


30 


31 


7-640 


.0109375 


.4375 


.44625 


.010 


. 008928 


.0116 


31 


32 


13-1280 


.01015625 


.40625 


.414375 


.009 


.00795 


.0108 


32 


33 


3-320 


.009375 


.375 


.3825 


.008 


.00708 


.0100 


33 


34 


11-1280 


.00859375 


.34375 


.350625 


.007 


.006304 


.0092 


34 


35 


5-640 


.0078125 


.3125 


.31875 


.005 


.005614 


.0084 


35 


36 


9-1280 


.00703125 


.28125 


.286875 


.004 


.005 


.0076 


36 


37 


17-2560 


.006640625 


.265625 


.2709375 




. 004453 


.0068 


37 


38 


1-160 


.00626 


.25 


.255 




.003965 
.003531 
.003144 


.0060 


38 
39 






40 









394 



APPENDIX 



ALLOWABLE VELOCITIES OF AIR THROUGH HEATERS 



NUMBER OF 

STACKS 
DEEP REG- 
ULAR 5-INCH 
CENTERS 


PUBLIC 

BUILDING WORK 

VELOCITY IN 

FEET PER 

MINUTE 


FACTORY WORK 

VELOCITY IN 

FEET PER 

MINUTE 


NUMBER OF 

STACKS DEEP 

REGULAR 

5-INCH CENTERS 


PUBLIC 

BUILDING WORK 

VELOCITY IN 

FEET PER 

MINUTE 


FACTORY WORK 

VELOCITY IN 

GEET PER 

MINUTE 


4 


1000 to 1500 


1200 to 1600 


7 


900 to 1100 


1200 to 1500 


5 


1000 to 1300 


1200 to 1600 


8 


800 to 1000 


1200 to 1400 


6 


1000 to 1200 


1200 to 1600 















PROPERTIES OF AIR 



w 


* K ~ 


!» H 


Ph H 


Ph H 


H 


^Ki 


>h Q H 


« H 


Ph W 


H 


pq w w 


M H S 


w H 


H H 


H 


n 3 3 


BHS 


M £> 


H H 


« 


« * w 


« ^ « i 


< W 


< K 


Ph 


-< Ph 


~ ^ w 


<! w 


«8 


O 


flKZ 


<J o 


^ O 


^ O 


O 


a < 


A <! o 




H 


W 5 H 

pq ^ S 


g « H 


s 


H 


H 


H W fe 


H « h 


H 


H 


^ 


9 p ft t. 


f-i o 


r" 


Q e 


Ph Ph r . 


P5 P o .. 


^ fi 


.' o 


Eh 


ABSOR 
T.DRY 
E FAH 


§ m « 3 


03 _. i4 


Eh 


EH 
Ph 3 


ABSOR 
FT. D 
EGREI 
T 


ABSOR 
T. SAT 
PER 
NHEIT 


EH 


Eh 
<^ P 


Ph &j 


*P§ 


. T. U. 
1 CU. I 
AIR 
FAHRF 


U. FT. 
WARM 
PER B 


U. FT. 
WARM 
PER B 


Ph W 
K 


. T. U. 
1 CU. 
PER D 
EN HE I 


. T. U. 
1 CU. F 
AIR 
FAHRE 


H § pq 

^^ Ph 


&; S pq 

^Ph 


Eh 


pq 


ffl 


u 


O 


Eh 


m 


pq 


O 


o 





0.02056 


0.02054 


48.5 


48.7 


102 


0.01682 


0.01731 


59.5 


57.8 


12 


0.02004 


0.02006 


50.1 


50.0 


112 


0.01651 


0.01711 


60.6 


58.5 


22 


0.01961 


0.01963 


51.1 


51.0 


122 


0.01623 


0.01691 


61.7 


59.1 


32 


0.01921 


0.01924 


52.0 


51.8 


132 


0.10596 


0.01670 


62.5 


59.9 


42 


0.01822 


0.01884 


53.2 


52.8 


142 


0.01571 


0.01652 


63.7 


60.6 


52 


0.01847 


0.01848 


54.0 


53.8 


152 


0.01544 


0.01654 


65.0 


60.5 


60 


0.01818 


0.01822 


55.0 


54.9 


162 


0.01518 


0.01656 


62.2 


60.4 


62 


0.01811 


0.01812 


56.2 


55.7 


172 


0.01494 


0.01658 


67.1 


60.3 


70 


0.01777 


0.01794 


57.3 


56.5 


182 


0.01471 


0.01687 


68.0 


59.5 


72 


0.01777 


0.01790 


58.5 


56.8 


192 


0.01449 




68.9 




82 


0.01744 


0.01770 


57.2 


56.5 


202 


0.01466 




68.5 




92 


0.01710 


0.01751 


58.5 


57.1 


212 


0.01406 




71.4 




100 


0.01690 


0.01735 


59.1 


57.8 













APPENDIX 



395 



VOLUME AND DENSITY OF DRY AIR AT VARIOUS 
TEMPERATURES 





VOLUME OF 1 




1 


VOLUME OF 1 






LB. OF AIR AT 


DENSITY OR 




LB. OF AIR AT 


DENSITY OR 


TEMP. 


ATMOSPHERIC 


■WEIGHT OF 1 




ATMOSPHERIC 


WEIGHT OF 1 


PRESSURE 


CU. FT. OF AIR 


TEMP. DEGREES 


PRESSURE 


CU. FT. OF AIR 




OF 14.7 LBS. 


AT 14.7 LBS. 


FAHRENHEIT 


OF 14.7 LBS. 


AT 14.7 LBS. 




ABS. TEMP. 


PRESSURE 




ABS. TEMP. 


PRESSURE 




FAHR. 459.2 


POUNDS 




FAHR. 459.2 


POUNDS 




CUBIC FEET 






CUBIC FEET 




-30 


10.821 


0.09241 


80 


13.593 


0.07358 


-20 


11.073 


0.09031 


90 


13.845 


0.07223 


-10 


11.325 


0.08830 


100 


14.097 


0.07094 


. 


11.577 


0.08638 


110 


14.349 


0.06969 


10 


11.829 


0.08454 


120 


14.601 


0.06849 


20 


12.081 


0.08278 


125 


14.728 


0.06790 


30 


12.334 


0.08108 


130 


14.854 


0.06732 


40 


12.586 


0.07945 


135 


14.980 


0.06676 


50 


12.838 


0.07789 


140 


15.106 


0.06620 


60 


13.090 


0.07639 


150 


15.358 


0.06511 


65 


13.216 


0.07567 


160 


15.610 


0.06406 


70 


13.342 


0.07495 









MOISTURE ABSORBED BY AIR 

The quantity of water which air is capable of absorbing to the point of 
maximum saturation, in grains per cubic foot for various temperatures 



DEGREES 


GRAINS IN A CUBIC 


DEGREES 


GRAINS IN A CUBIC 


FAHRENHEIT 


FOOT 


FAHRENHEIT 


FOOT 


10 


1.1 


85 


12.43 


15 


1.31 


90 


14.38 


20 


1.56 


95 


16.60 


25 


1.85 


100 


19.12 


30 


2.19 


105 


22.0 


32 


2.35 


110 


25.5 


35 


2.59 


115 


30.0 


40 


3.06 


130 


42.5 


45 


3.61 


141 


58.0 


50 


4.24 


157 


85.0 


55 


4.97 


170 


112.5 


60 


5.82 


179 


138.0 


65 


6.81 


188 


166.0 


70 


7.94 


195 


194.0 


75 


9.24 


212 


265.0 


80 


10.73 







396 



APPENDIX 



AIR 

Loss of pressure in ounces per square inch for 100 feet length for varying 
velocities and varying diameters of pipes 



VELOC- 
ITY OF 


DIAMETER OF PIPE IN INCHES 


AIR 

FEET 


1 


2 


3 


4 


5 


6 


7 


8 


PER 
MINUTE 


Loss of Pressure in Ounces 



600 


.400 


.200 


.133 


.100 


.080 


.067 


.057 


1,200 


1.600 


.800 


.533 


.400 


.320 


.267 


.229 


1,800 


3.600 


1.800 


1.200 


.900 


.720 


.600 


.514 


2,400 


6.400 


3.200 


2.133 


1.600 


1.280 


1.067 


.914 


3,000 


10.000 


5.000 


3.333 


2.500 


2.000 


1.667 


1.429 


3,600 


14.400 


7.200 


4.800 


3.600 


2.880 


2.400 


2.057 


4,200 




9.800 


6.553 


4.900 


3.920 


3.267 


2.800 


4,800 




12.800 


8.533 


6.400 


5.120 


4.267 


3.657 


6,000 




20.000 


13.333 


10.000 


8.000 


6.667 


5.714 



600 
1,200 
1,800 
2,400 
3,000 
3,600 
4,200 
4,800 
6,000 



.044 


.040 


.036 


.033 


.029 


.026 


.022 


.178 


.160 


.145 


.133 


.114 


.100 


.089 


.400 


.360 


.327 


.300 


.257 


.225 


.200 


.711 


.640 


.582 


.533 


.457 


.400 


.356 


1.111 


1.000 


.909 


.833 








1.600 


1.440 


1.309 


1.200 


1.029 


.900 


.800 


2.178 


1.960 


1.782 


1.633 


1.400 


1.225 


1.089 


2.844 


2.560 


2.327 


2.133 


1.829 


1.600 


1.422 


4.444 


4.000 


3.636 


3.333 


2.857 


2.500 


2.222 



600 


.018 


.017 


.014 


.012 


.011 


.010 


.009 


1,200 


.073 


.067 


.057 


.050 


.044 


.040 


.036 


1,800 


.164 


.156 


.129 


.112 


.100 


.090 


.082 


2,400 


.291 


.267 


.239 


.200 


.178 


.160 


.145 


3,600 


.655 


.600 


.514 


.450 


.400 


.360 


.327 


4,200 


.891 


.817 


.700 


.612 


.544 


.490 


.445 


4,800 


1.164 


1.067 


.914 


.800 


.711 


.640 


.582 


6,000 


1.818 


1.667 


1.429 


1.250 


1.111 


1.000 


.909 



.050 

.200 

.450 

.800 

1.250 

1.800 

2.450 

3.200 

5.000 



VELOC- 
ITY OF 


DIAMETER OF PIPE IN INCHES 


AIR 

FEET 


9 


10 


11 


12 


14 


16 * 


18 


20 


PER 
MINUTE 


Loss of Pressure in Ounces 



.020 
.080 
.180 
.320 

.720 

.980 

1.280 

2.000 



VELOC- 
ITY OF 


DIAMETER OF PIPE IN INCHES 


AIR 

FEET 


22 


24 


28 


32 


36 


40 


44 


48 


PER 

MINUTE 


Loss of Pressure in Ounces 



.008 
.033 
.075 
.133 
.300 
.408 
.533 
.833 



WEIGHTS OF GALVANIZED IRON PIPE PER LINEAL FOOT 



DIAMETER 




GAUGE OF IRON — NUMBERS 




OF PIPE IN 










INCHES 


18 


20 


22 24 


26 


3 


21 


H 


1! 


H 


1 


4 


2f 


21 


1! 


1! 


u 


5 


3| 


2f 


2 


If 


1! 


6 


32 


3 


21 


2 


if 


7 


4! 


3! 


21 


21 


2 


8 


5| 


4 


3 


3f 


21 


9 


5f 


4! 


31 


3 


2| 


10 


6| 


4f 


OT> 


31 


2! 


11 


6f 


51 


3| 


3! 


2f 


12 


7i 

' 2 


51 


. 41 


3f 


3 


13 


8 


61 


4! 


4 


31 


14 


8§ 


61 


4f 


41 


3! 


15 


91 


7 A 


51 


4f 


3! 


16 


91 


7^ 

« 4 


«-»2 


5 


4 


17 


10| 


8 


6 


51 


41 


18 


lOf 


8! 


61 


5! 


4! 


19 


11§ 


9 


6| 


5f 


4f 


20 


12 


9! 


7 1 


5 


51 


21 


12| 


9f 


7! 


5! 


5! 


22 


- 131 


101 


7f < 


5f 


5f 


23 


14 


11 


81 


7 


6 


24 


14f 


11* 


8f 


r! 


6! 


26 


15f 


12! 


91 


rf 


6! 


28 


16| 


13! 


9f J 


3! 


7 


30 


18 


14 


10! i 


3 


7i 

' 2 


32 


m 


15 


111 ! 


?! 


8 


34 


201 


15f 


12 1( 


)1 


8! 


' 36 


21| 


16| 


12! H 


)i 


9 


38 


221 


18 


13! 1 


Li 


9! 


40 


24 


18f 


14 i: 


2 


10 


42 


25 


19! 


14f V 


2! 


10! 


44 


261 


20! 


is! i; 


5 


n 


46 


27! 


211 


16 i; 


5! 


m 


48 


28| 


221 


16| 1' 


H 


12 


50 


29| 


23 


17! u 




12! 


52 


311 


241 


181 








54 


32| 


25 


18f 








56 


33| 


26 


19 








58 


35 


26| 


201 








60 


361 


27! 


20f 








63 


381 


29 


21f 








66 


40 


301 


22f 








69 


41f 


321 


23f 








72 


43| 


331 


25 









The figures in bold faced type represent weight of round piping ordi- 
narily used in heating work. 

Figures include amount required to make joints but do not allow for 
waste in cutting which generally averages about 15 per cent. 

397 



398 



APPENDIX 



HEAT TRANSFERENCE TABLES 

B.t.u. given up by 1 cu. ft. of air cooling from discharge outlet temperature 
to temperature inside building. 



si 


OUTLET TEMPERATURES 


K w t, 

13 & m 






























TEMPERA 
SIDE 
DEGEEI 


180 


170 


160 


150 


145 


140 


135 


130 


125 


120 


115 


110 


100 


90 


80 


1.474 


1.348 


1.218 


1.082 


1.015 


0.944 


0.872 


0.800 


0.726 


0.651 


0.574 


0.497 


0.337 


0.172 


70 


1.622 


1.499 


1.370 


1.238 


1.170 


1.101 


1.032 


0.960 


0.887 


0.814 


0.738 


0.662 


0.505 


0.343 


65 


1.696 


1.573 


1.447 


1.314 


1.248 


1.180 


1.110 


1.040 


0.968 


0.895 


0.821 


0.745 


0.589 


0.428 


60 


1.770 


1.649 


1.522 


1.392 


1.325 


1.258 


1.190 


1.120 


1.049 


0.977 


0.903 


0.828 


0.674 


0.514 


55 


1.844 


1.723 


1.599 


1.470 


1.404 


1.336 


1.270 


1.200 


1.129 


1.058 


0.985 


0.911 


0.758 


0.601 


50 


1.918 


1.798 


1.675 


1.547 


1.481 


1.415 


1.348 


1.280 


1.210 


1.139 


1.068 


0.994 


0.843 


0.686 



Factors for reducing air volume at discharge outlet temperature to eauivalent 
air volume at 140° F. and 70° F. 



A a 
% a 




























































H O <o 
a & H 


180 


170 


160 


150 


145 


140 


135 


130 


125 


120 


115 


110 


100 


90 


j < a 






























& « « 






























P a o 
o 






























140 


0.938 


0.952 


0.967 


0.984 


0.992 


1.000 


1.008 


1.016 


1.025 


1.034 


1.043 


1.052 


1.071 


1.090 


70 


0.828 


0.842 


0.855 


0.869 


0.877 


0.884 


0.892 


0.899 


0.907 


0.914 


0.922 


0.931 


0.947 


0.964 



B.T.U. REQUIRED FOR HEATING AIR 

This table specifies the quantity of heat in B. t. u. required to raise 1 
cubic foot of air through any given temperature interval. 



EXTER- 
NAL 
TEMPER- 








TEMPEEATURE ( 


)F AIR IN ROOM 








DEGREES 
F. 


40 


50 


60 


70 


80 


90 


100 


110 


120 


130 


-40 


1.802 


2.027 


2.252 


2.479 


2.703 


2.928 


3.154 


3.379 


3.604 


3.829 


-30 


1.540 


1.760 


1.980 


2.200 


2.420 


2.640 


2.860 


3.080 


3.300 


3.520 


-20 


1.290 


1.505 


1.720 


1.935 


2.150 


2.365 


2.580 


2.795 


3.010 


3.225 


-10 


1.051 


1.262 


1.473 


1.684 


1.892 


2.102 


2.311 


2.522 


2.732 


2.943 





0.822 


1.028 


1.234 


1.439 


1.645 


1.851 


2.056 


2.262 


2.467 


2.673 


10 


0.604 


0.805 


1.007 


1.208 


1.409 


1.611 


1.812 


2.013 


2.215 


2.416 


20 


0.393 


0.590 


0.787 


0.984 


1.181 


1.378 


1.575 


1.771 


1.958 


2.165 


30 


0.192 


0.385 


0.578 


0.770 


0.963 


1.155 


1.345 


1.540 


1.733 


1.925 


40 


0.000 


0.188 


0.376 


0.564 


0.752 


0.940 


1.128 


1.316 


1.504 


1.692 


50 


0.000 


0.000 


0.184 


0.367 


0.551 


0.735 


0.918 


1.102 


1.286 


1.470 


60 


0.000 


0.000 


0.000 


0.179 


0.359 


0.538 


0.718 


0.897 


1.077 


1.256 


70 


0.000 


0.000 


0.000 


0.000 


0.175 


0.350 


0.525 


0.700 


0.875 


1.049 



INDEX 

Air, B. t. u. required for heating 398 

distribution systems 51 

dry, volume and density of, at various temperatures 395 

ducts and flues 105 

pipes, proportioning 92 

pressure, loss of, for varying velocities and diameters of pipe. . 396 

properties of 394 

removal, mechanical systems of 66 

removal system, specification for 67 

through heaters, allowable velocities of * . 394 

Air washers 56 

frictional resistance 57 

preferable velocities 57 

pumps 57 

temperature losses 58 

Anchors for hot water heating pipes 127 

Belt, horsepower of a leather : 390 

Bends, air pipe , 54 

Blast heaters, condensation and temperature tables 37-50 

Boilers, dimensions of standard U. S. tubular, for low pressure heating 

work , 383 

fire box 19 

portable steel 20 

rooms, kitchens, etc., ventilation of 102 

water heating 136 

By-passes, air 53 

Classification of systems 370 

Central plant equipment, hot water heating 134 

Clocks, time, conduit systems for, and other special purposes 214 

tower 216 

Cloth filters 108 

Conduits for hot water heating , 126 

Connections, minimum height of, off pipe mains 385 

Cost, estimating data for heating and ventilating apparatus in new 

federal buildings 69 

of lighting fixtures, estimating 227 

Costs of heating equipment 110 

Dampers and deflectors, air 56 

Distillery warehouses, heating of 98 

Drinking water fountains and faucets 168 

water systems, estimating cost of 172 

water systems, specification for 173 

Ducts, air, resistance of 54 

Electric conduit and wiring systems 197 

lighting, general illumination 204 

lighting, load factors 206 

lighting, outlets 200 

lighting, estimating data 211 

lighting, voltage drop 206 

lighting, wire and cable data 210 

lighting and wiring formulae and tables 207 

motors and controlling apparatus 306 

399 



400 INDEX 

i 

Electric conduit and wiring systems — Continued 

direct current 306 

alternating current 310 

phase-wound induction motors 313 

Elevator, specification for, electric passenger 254 

Elevators 235 

alternating current electric, specifications for 269 

cables and counterweights for 248 

instructions relative to the inspection and test of new 275 

loads of cars 240 

size of cars 237 

space requirements, etc., for 244 

speeds of cars 239 

tanks, pumps, etc., for 249 

types of 241 

Engines and generators, specification for 293 

types of 284 

Equalization table, air ducts 55 

Estimating data for heating and ventilating apparatus in new federal 

buildings 69 

Exhaust ventilation, systems of 101 

Expansion of wrought iron pipes 126 

Expansion tank 136 

Factory heating 75 

heating, ducts and flues 84 

heating, fan systems for 76, 90 

heating, humidifiers for 83 

heating, prime movers for 82 

heating, steam and return piping for 81 

heating, systems of air distribution 85 

Fan systems 22 

systems, air to be circulated with 23 

Fans, capacity and power of 23, .90, 105 

cone 25 

double inlet 59 

kind and size of 23 

multiblade 24 

properties of Ill 

shop testing of 59 

speed of 26 

steel plate 24 

Federal buildings, estimating data for heating and ventilating appara- 
tus in new 69 

Filters, cloth 108 

Fire alarm and watchman's time detector system 219 

Flues and registers, vertical air 53 

Foul air removal 105 

Foundries, heating of 98 

Gas piping 193 

piping, specification 193 

Gauges and thermometers 136 

Generating units, size and number of, for small power plants 281 

Generators, electric 291 

engines, and, specification for 293 

Heat available per pound of exhaust steam 135 

losses through building materials 8, 86 

specific, of bodies 389 

transference tables 398 



INDEX 401 

Heater connections, hot water, size of 135 

Heaters 26 

blast, condensation and temperature tables 37-50 

friction in 26 

hot water, exhaust and live steam 134 

Vento 27 

and temporing coils 104 

Heating, double duct system 106 

factory 75 

of distillery warehouses 98 

of foundries 98 

of hotels, etc 104 

of paper mills 97 

of planing mills 99 

of railroad round houses 100 

of school houses 104 

of textile mills 97 

systems, two pipe gravity steam 18 

and ventilating new federal buildings, estimating data for 69 

Hot water heating regulation 124 

heating system, limitations of 125 

heating with wrought iron coils 28 

Hotels, etc., heating of 104 

Humidifying systems 57 

Ice water cooling plant, methods of calculation 169 

Instructions, general, issued to draftsmen 363 

Kitchen, boiler rooms, etc., ventilation of 102 

Lighting fixtures, basic data in connection with design and installa- 
tion of. 225 

fixtures, estimating cost of 227 

fixtures, schedule of 233 

fixtures, specifications for 228 

Loss in pressure due to friction in water pipe 389 

Mains, layout of hot water heating 128 

Manholes 127 

Mechanical systems of air removal 66, 88 

Moisture absorbed by air 382 

Operating data 343 

Paper mills, heating of 97 

Pipe sizes 16,91 

standard dimension of 383 

weights of galvanized iron 397 

Piping dimensions of 14 

equalizing table 15 

steam and return 57 

Planing mills, heating of 99 

Plenum chambers 53 

Plumbing, drainage and water supply 137 

drinking water supply 161 

report of committee on toilet regulations in industrial plants... 149 

specification, uniform 146 

systems, water supply for 151 

and drainage systems, estimating data for 186 

and drainage system, test of 184 

Power plants, small 278 

Pressure in inches of water and corresponding pressures and velocities 392 

in ounches with corresponding velocities 392 

loss due to friction, in water pipe 389 



402 INDEX 

Prime movers 51 

Pump, circulating 135 

Pumps, vacuum _ 92 

Radiating surface, basis for calculating 7 

Radiation, direct-indirect 12 

gravity, indirect 13 

hot water, in individual buildings 128 

Radiator connections for hot water heating 130 

Railroad round houses, heating of 100 

Refrigeration 163 

data 391 

Registers, grilles, etc 106 

School houses, heating of 104 

Signal systems, conduit for 224 

Specification for air removal system 67 

drinking water systems 173 

for electric passenger elevator 254 

for engines and generators 293 

for gas piping 193 

for vacuum cleaning systems 326 

uniform plumbing 146 

Specifications for lighting fixtures 228 

Steam, table of the properties of saturated 387 

Steel, weights of 393 

Superintendents, suggestions to 373 

Switchboard, electric 211 

Systems, classification of 370 

Tanks, capacity of cylindrical 384 

expansion 388 

Telephone and call bell conduits 221 

Temperature regulators, automatic 1C7 

Temperatures, climatic 386 

Tempering coils, heaters and 105 

Testing heating systems, relative temperatures for 109 

Textile mills, heating of 97 

Toilet rooms, ventilation of 101 

Vacuum cleaning systems 316 

cleaning system, specification for four-sweeper plant 326 

cleaning system, specification for portable apparatus 340 

heating systems 62, 88 

heating systems, pumps 64 

Valves for hot water heating 127 

Vapor systems, use of 6 

Vault protection system 220 

Ventilation, amount of air for 108 

of kitchens, boiler rooms, etc 102 

of toilet rooms 101 

plenum chamber system 103 

systems of exhaust 101 

Vento heaters _ 27, 29-35 

Water required to be circulated in hot water heating 130 

supply, drinking 161 

table giving velocity of flow of, through pipes of various sizes 388 

Weather bureau special conduits 223 









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